Linux Not Quite Ready For New 4K-Sector Drives

Theovon writes "We've seen a few stories recently about the new Western Digital Green drives. According to WD, their new 4096-byte sector drives are problematic for Windows XP users but not Linux or most other OSes. Linux users should not be complacent about this, because not all the Linux tools like fdisk have caught up. The result is a reduction in write throughput by a factor of 3.3 across the board (a 230% overhead) when 4096-byte clusters are misaligned to 4096-byte physical sectors by one or more 512-byte logical sectors. The author does some benchmarks to demonstrate this. Also, from the comments on the article, it appears that even parted is not ready, since by default it aligns to 'cylinder' boundaries, which are not physical cylinder boundaries and are multiples of 63."

Comments

first misaligned post

[Anonymous Coward]

damnit, obviously since this is not technically the 'first post', my web browser must be misaligned by a post

oh great.. i try to make a joke and ...

[decora]

the first time i have ever actually gotten 'first post'... it is when i try to make a joke about not having gotten first post. ya see my first post was supposed to come up like second or third.. it would have been HILARIOUS . .. but oh no in soviet russia, the fates mock you!!!!

Set 32 sectors per track

[tchuladdiass]

The simple solution is to set you Sectors per Track to 32. This would make sure that everything is properly aligned (except the first partition, usually /boot, which is mis-aligned by one cylinder).

Re:Set 32 sectors per track

[Brian Gordon]

Sectors, blocks, clusters, cylinders... I hope that as we move to solid state drives, devs have the sense to exorcise these anachronisms from the kernel. We haven't been able to get rid of terminals in the 20 years since they've even existed.. this document is heart wrenching. Try reading it; it'll make you cry to see how deeply the now-irrelevant concept of a terminal runs in Linux.

Re:Set 32 sectors per track

[walshy007]

the now-irrelevant concept of a terminal

Speak for yourself sir, I for one like my rs-232 terminals to be handy for when ethernet is down and you can't ssh (and can't be assed hooking up keyboard and monitor). Seriously, anyone adept at the command line uses it far more than the gui to get things done, terminals will never disappear.

Re:Set 32 sectors per track

[rubycodez]

terminals are a very necessary and relevant part of Linux. That's how most server administration is done. That's how sending commands to many network appliances is done. That's how setting up high end computers is done (e.g. set up a midrange Integrity or Superdome and you'll start with terminal on the serial port, whether cu in linux or hyperterminal in windowws or a real terminal). Also how certain tasks are performed in GUI environments. It doesn't matter that the terminal is now mostly virtual, the cursor control and font attribute features make convenient applications possible. Even on the weekend here I am chatting via IRC to some tech friends with irssi in terminal under screen, and reading server status emails with mutt. the terminal, it's 21st century tool.

Re:Set 32 sectors per track

[Anonymous Coward]

terminals have nothing to do with the command line!
i think the op is complaining about the fact that things like
baud, stopbits and whatnot are deeply embedded in the
linux kernel. these concepts are not necessary to
have a command line. c.f. plan 9.

Re:Set 32 sectors per track

[Z00L00K]

Essentially we are back to the old problems of the ST412 interface where we had to figure out the best interleave for the drives as well when we were formatting them. Most drives then did have a fairly conservative interleave, but a reformat of them could improve the throughput considerably. A reformat could be done so that the whole track could be read in 2 rotations instead of 3, and what that does to performance is fairly easy to understand. C800:5 was a commonly used BIOS address where the low level format routine did reside.

But from what I understand this problem is an offset problem when the head steps from track to track, and that's also an issue to be considered. And today it's not common knowledge/practice to low level format hard drives.

And why stick at 4k sectors? Depending on the system you may want to use a different sector size. If you run Oracle on some systems the block size is 8k, and in that case you may want to have 8k disk blocks too since it would be good for performance.

Anyway - sooner or later we will have flash drives instead, and then this isn't a problem.

Re:Set 32 sectors per track

[amorsen]

Anyway - sooner or later we will have flash drives instead, and then this isn't a problem.

Actually this problem is potentially much worse on SSD's. Erase blocks are huge, and read-modify-write really sucks on flash.

Re:Set 32 sectors per track

[blincoln]

Actually this problem is potentially much worse on SSD's. Erase blocks are huge, and read-modify-write really sucks on flash.

Couldn't this be addressed (at least in part) by a battery-backed write cache like better RAID controllers use? Set it up like SAN snapshots (so it just stores the diff between what's in the actual flash storage and what's been changed so far), and then write the changed blocks when it's most advantageous (e.g. when there's an entire block's worth of data, so it would all have to be erased by the flash storage anyway).
Maybe combine that with something like a disk defrag, except instead of storing frequently-sequentially-read data in physical sequence, store frequently-written data (regardless of if it's sequentially-read or not) in physical sequence.

Re:Set 32 sectors per track

[kimvette]

The terminal is not irrelevant. If your Cisco router is ever compromised (it happens) or if IOS becomes corrupt (or if you have an IOS install with a nasty bug where the password does not save correctly, or when an IOS upgrade goes badly) or someone fudges the configuration up, the only way you can recover it is often through the serial port. Serial ports are also very handy for integrating video surveillance with point-of-sales systems that are not IP-aware (or worse, antiquated DVR appliances which can't do POS integration over IP), for some smart switches, *NIX boxes that have been rooted (I've rescued a Solaris box through a serial connection in an enterprise environment where reinstall was not possible due to poor timing - week of finals - and backups were sabotaged by a disgruntled gradute student and logins through IP and at the console were blocked), and so forth. However, I'd rather see RS-485 or RS-422 take RS232's place, since RS-485 and RS-422 can work over much longer distances and you can hang multiple serial devices off of a single bus.

RS-232 might be absent from a lot of consumer motherboards, but it is far from dead and certainly not irrelevant, even now in 2010.

Re:Set 32 sectors per track

[kimvette]

Oh, in addition, now that Windows Server (Core) has a real GUI-less mode and Powershell and UNIX environment shells on Windows finally have usable interfaces, shell prompts are becoming even more relevant even in large Window shops. So, even Microsoft has acknowledged that the UNIX-y way of doing things is key for automation and uptime in an enterprise environment. Now, most PCs won't boot with output to the serial port, but some enterprise server boards do have such options.

A GUI is great for basic tasks, but for repetitive tasks a command shell and scripting environment are key for efficiency, and reliable automation. VBS/Windows Scripting Host was an "acceptable" workaround for a while but in the past many Windows administrative tools required the box to not be headless, the workstation unlocked and the windows open for the GUI to be accessible for scripting - and even then it was iffy because not all GUI elements are accessible (especially third-party tools with custom controls).

Re:Set 32 sectors per track

[bertok]

Actually this problem is potentially much worse on SSD's. Erase blocks are huge, and read-modify-write really sucks on flash.

Couldn't this be addressed (at least in part) by a battery-backed write cache like better RAID controllers use? Set it up like SAN snapshots (so it just stores the diff between what's in the actual flash storage and what's been changed so far), and then write the changed blocks when it's most advantageous (e.g. when there's an entire block's worth of data, so it would all have to be erased by the flash storage anyway).
Maybe combine that with something like a disk defrag, except instead of storing frequently-sequentially-read data in physical sequence, store frequently-written data (regardless of if it's sequentially-read or not) in physical sequence.

That's exactly what most SSD controllers do!

Some now come with 32 to 64MB of cache, and some of the new Sandforce controller based SSDs also come with a little ultracapacitor that acts like a mini UPS. The cache is used as scratch space for reordering writes and defragging blocks.

There was a firmware patch recently for the OCZ Vertex series of SSDs that enabled background defrag. If you let the drive site there for a few minutes, it would start getting faster until it returned to 'as new' speeds

Re:Set 32 sectors per track

[orkysoft]

I recommend you visit Microsoft and have a look at their "Windows" operating system. The concept of a terminal doesn't run nearly as deep in it as it does in Linux. The same goes for the concept of security. Overall, it is kind of a poorly reinvented UNIX, but I think you might just like it. There are quite a few applications available for it nowadays, and it is gaining more and more marketshare and public recognition.

Re:Set 32 sectors per track

[MobileTatsu-NJG]

We both agreed that most of windows land involves emailing shit to yourself, and a lot of USB thumb drive use...

Explorer: \\ComputerName\c$\Documents and Settings\UserName\My Documents\

Permissions permitting, this is all you need to do. Or you just share folders.

(Of which I could fire off a good half-hour rant on how poorly windows handles mass storage devices. It's a USB THUMB DRIVE for gods sake. It's not a fucking printer! I want to plug it in, and transfer files to/from it. It doesn't need to be "installed", indexed, and have drivers downloaded for it. Just fucking open a file browser like any sane OS does. )

This is a 10 year old complaint.

I have a hard time working on windows, because I'm so much more efficient with a terminal. It's not that I can't use a gui - I'm just an order of magnitude faster using the terminal.

That and you're not using Windows properly.

Re:Set 32 sectors per track

[Anonymous Coward]

I don't think he was dissing command line interfaces.

I think his complaint was that even newfangled RS-232 terminals had to jump through hoops to remain compatible with computers that were hooked up to typewriters and line printers. The protocols and underlying software have idiosyncrasies built into them that just don't make sense any more. Instead of throwing away the cruft to make something better, everybody's hacking onto the same old outdated shit. It's limiting progress, in a way.

Re:Set 32 sectors per track

[cerberusss]

I recommend you visit Microsoft and have a look at their "Windows" operating system. [...] Overall, it is kind of a poorly reinvented UNIX, but I think you might just like it.

I've seen some people use it, then they told me you had to pay for it. I was flabbergasted -- why would anyone pay for an operating system?

Good thread on this.

[Anonymous Coward]

http://www.osnews.com/thread?409281

Re:Good thread on this.

[Anonymous Coward]

The BIOS has no understanding of partition tables. It merely reads the first sector of the harddrive to 0x7C00 and then jumps to that location. The DOS partition table is used by convention for interoperability between operating systems. If you wanted to use a different partitioning scheme, there is no technical reason your operating system couldn't.

Re:Good thread on this.

[Anonymous Coward]

GPT wraps itself in a MBR partition map. At the very least the GPT is supposed to include an MBR map that claims the whole disk as used by GPT to avoid issues with old disk tools and the like. And if you've got a partition scheme that's compatible with the MBR scheme they can both contain the same information, assuming your disk tool supports this, so that MBR-only environments can still find your partitions.

It's also possible to format with GPT and then use an MBR-only tool (fdisk) to go back and manipulate the (fake) MBR to contain a partition that points to the same start/end points as the GPT boot partition -- GPT-aware systems will just ignore the MBR record, and non-GPT systems will at least be able to find the boot partition.

As to whether your motherboard/firmware supports GPT, it can be hard to say. Anything with EFI is required to support GPT. Some systems with a legacy BIOS pre-boot environment also have support for GPT, because it's the only way to support large disks. But I can't name particular firmware versions that do/don't support GPT.

Re:Good thread on this.

[marcansoft]

Unless your BIOS is trying to be too smart and peeking into your partitions instead of launching the MBR (sadly, some do), it won't matter. It's the MBR's job to boot your system after the BIOS hands off control to it, and on most Linux systems the bootloader is installed straight into the MBR.

Re:Good thread on this.

[Z34107]

Even if you are using Windows, Vista and up support GPT. It's handy for servers where you expect to have partitions larger than 2 TB.

But I guess if one were using a modern version of Windows, you wouldn't have the 4K alignment problems to begin with.

Open Source to the rescue

[bogaboga]

I am no kernel hacker but I can almost guarantee that some kernel hacker will provide a solution to this "short coming" fairly soon.

That's the beauty of Open Source.

I am aware though that "fairly soon" means many things to many people; which means that there could be a substantial delay before we get a working solution to this issue.

I am optimistic nevertheless.

Request to Western Digital: Provide all the information needed to develop a solution.

Re:Open Source to the rescue

[marcansoft]

Exactly. Drives are pretending to have 512-byte sectors because Windows can't deal with 4k sectors, and then silently reducing performance when you believe them and use 512-byte sector sizes. Had the drives reported 4k sector sizes, they'd work great under Linux and not at all under Windows.

This isn't a Linux problem, it's a drive problem caused by Windows. The solution is to implement yet another workaround for stupid devices, and start aligning partitions to 4k by default.

Nitpick: SDHC card sectors are always 512 bytes, and most SD card sectors are 512 bytes too. Flash memory would benefit from larger sector sizes too, but they've probably stuck to 512 bytes for Windows compatibility.

Re:Open Source to the rescue

[Pentium100]

Now I wonder why a hard drive company feels the need to have it's hardware LIE to the OS?

So the hardware is compatible with more software. For example, hard drives still report some number of cylinders, heads and sectors to the BIOS and the OS, but hard drives have been using ZBR for 20 years now (IIRC) so the sector number is meaningless.

But, as it is now, if my old system needs a new hard drive, I do not need to find an old drive to be compatible with my system (as long as it is IDE or SCSI, I don't know of any adapter from the newer interfaces to ESDI or ST-506, but they probably exist).

They could have made it a jumper setting set to 512B by default though. I assume the hard drive is faster using 4KB sectors instead of true 512B sectors, they could have made an option to reformat the drive to 512B (or maybe it's not possible with modern drives, I have an old 4GB SCSI drive that can be reformatted to a different sector size (I never tried it though)).

Re:Open Source to the rescue

[rsmith-mac]

On the contrary, this has (almost) nothing to do with Windows - it has everything to do with old OSes. The IDEMA didn't approve the 4K sector standard until 2006; it was only in the late 90's that the first meaningful research was begun by IBM on whether 512B sectors would be an issue.

As it turns out, yes, 512B sectors would be an issue, and drive manufacturers would be best served by moving to larger sectors (with some arguing over whether to go to 1K or 4K). So the IDEMA hashed this out over the first half of the decade, and finally in 2006 approved the 4K specification.

The point of all of this is that software written at the turn of the century was all done well before changing drive sector sizes was a serious discussion. WinXP was released in 2001, Mac OS X 10.0 was in 2001, and of course Linux 2.4 was also in 2001. None of those OSes know what to do with anything other than a 512B sector - the only reason Windows factors in to this equation is that WinXP just happens to be with us (no doubt trying to eat our brains) while the other two are dead. Anything circa 2005 or later such as WinVista, Linux 2.6, and Mac OS X 10.5 know full well what to do with a 4K drive.

But even that is beside the point. You don't just make major jumps like this, you have to do it in a transition so that you don't break old hardware and old software alike. Even if XP/Lin2.4/MacOSX knew what to do with 4K sectors, at some point you'd run in to hardware, 3rd party devices, etc that would not. A transition is necessary to let old hardware and software get flushed out of the ecosystem, and as such we're still years out from consumer drives offering native 4K access.

In short: drives are pretending to have 512-byte sectors because there's a lot of old stuff, including Windows XP that can't deal with 4K sectors.

Re:Open Source to the rescue

[DAldredge]

Drives have been lying to the OS for more than 20 years in regards to quite a few different things so why pick now to yell and get upset?

Re:Open Source to the rescue

[marcansoft]

I was referring to Windows XP - I should've mentioned it explicitly. Nonetheless,

There's a lot of old stuff, including Windows XP that can't deal with 4K sectors.

There's exactly one old thing used in any significant quantity and liable to have to work with these drives, and it's Windows XP. Everything else either isn't in any significant use any more, or will never be seeing one of these drives.

One potential concern would be USB enclosures which have to work with older OSes / devices. To that, I would say it should be the enclosure's job to do the 512-byte sector emulator, not the drive's.

Windows XP has been updated over the years (via service packs and the like) to handle hardware that didn't exist at the time of its release, including things like SATA. They could do the same for 4k sector disks, but they aren't going to do it because they want people to move to Win7. Therefore, Microsoft is still to blame for neither 1) providing a solution for XP, nor 2) providing enough compelling reasons to migrate to Win7. Heck, Vista was a trainwreck and it doesn't really count, so (proper) Windows is actually 3 years late to the 4k party, as Windows 7 was only released in 2009. Effectively, they've spent those three years scaling down support for XP while providing no viable alternative, and now the rest of the world has to deal with a significant amount of people still using a 9-year-old OS.

In short: the fact that people are sticking to 9-year-old XP and making hardware companies break or slow down improvements means Microsoft did something terribly wrong.

Re:Open Source to the rescue

[guruevi]

Ya know in the olden days, when I was young (love saying that) we didn't have hardware that configured itself so it would work on all platforms. We had to put in settings with jumpers and do low-level disk formats through the BIOS or a boot-floppy and WE LIKED IT (seriously).

These days all ya new-fangled hardware doesn't have to worry about being a master or a slave, getting 5V or 3.3V to the PCI bus or RAM modules, CPU multipliers on the motherboard.

I would simply do the same - get a jumper on the back of the drive that says 512 or 4k - we left it on 512 for ya because we assume you numbnuts still use Windows (XP) but if you want performance and use anything but DOS or WinDOS feel free to switch it. You can then reformat the drive.

Re:Open Source to the rescue

[IgnoramusMaximus]

... and of course Linux 2.4 was also in 2001. None of those OSes know what to do with anything other than a 512B sector -

And...

... Linux 2.6, and Mac OS X 10.5 know full well what to do with a 4K drive.

Total bullshit.

Linux kernel code had flexible block device sector size since the days of 1.x series of kernels. The "problem" is (and always was) with some of the user-space utilities for some of the file systems available under Linux, file systems specifically designed for ... compatibility with DOS and Windows (and through them with the original, ancient IBM PC XT BIOS).

Even then most of the same utilities have various override options that can be used to make them compliant with "unusual" (from the point of view of Windows) sector/block sizes and dive geometries, although it is not their default behavior. The very article you are responding to moans about this very thing, as if it were any news to long-time Linux users.

Windows apologists and their revisionist history are just pathetic.

Re:Interesting

[ScytheBlade1]

TFA disagrees with you.

$ time cp winxp.img /mnt/sdc # ALIGNED
real 5m9.360s
user 0m0.090s
sys 0m20.420s

$ time cp winxp.img /mnt/sdd # UNALIGNED
real 13m26.943s
user 0m0.110s
sys 0m19.350s

$ time cp -r Computer Architecture/ /mnt/sdc # ALIGNED
real 42m9.602s
user 0m0.680s
sys 1m59.070s

$ time cp -r Computer Architecture/ /mnt/sdd # UNALIGNED
real 138m54.610s
user 0m0.660s
sys 2m15.630s

The first two being a single file, the latter two being multiple files in a larger directory structure.

I would heartily disagree with you on the matter.

Check with your distribution

[macemoneta]

I know that Fedora seems to have addressed this with parted 2.1.1 and util-linux-ng 2.1. Both are scheduled for Fedora 13, but can be pulled into Fedora 12 by those getting the hardware early.

Oh slashdot..

[JeffSh]

Dear Slashdot,

I've been around for a while. Enough to understand, nay, love the fact that you are linux supporters and all that. But I remain an ardent supporter of truth and speaking in ways which are concise and leads the reader in the direction of truth. Nothing in this news story is inaccurate, but to make it a point to say that Windows XP is incompatible with no mention of Vista and 7 being perfectly compatible should be an embarrassment of journalistic integrity.

Windows XP may not work with the new WD Green drives, but Vista and on have been perfectly comfortable with 4096 byte sectors. A lay reader may read this story and not "Read between the lines" as I have learned to do here. Their take away may be that Microsoft operating systems are broken in some way (which they are in a lot of ways), but not this one!

Re:Oh slashdot..

[Vellmont]

  but to make it a point to say that Windows XP is incompatible with no mention of Vista and 7 being perfectly compatible should be an embarrassment of journalistic integrity.
.
.
Their take away may be that Microsoft operating systems are broken in some way (which they are in a lot of ways), but not this one!

It only takes about 3 brain cells to realize that Windows XP != All Microsoft Operating Systems. Even the average person has more than 3 brain cells.

For those people with less than 3 brain cells, Slashdot still has you covered since the article clearly says:

According to WD, their new 4096-byte sector drives are problematic for Windows XP users but not Linux or most other OSes.

(emphasis mine)
It only takes 2 brain cells to understand that "most other OSes" likely includes Vista and Windows 7.

For those unlucky few with only 1 brain cell, you're correct. Slashdot has certainly failed the 1 brain celled individual.

Re:So don't do that...

[marcansoft]

fdisk doesn't need to be fixed, it needs to be deprecated. DOS partition tables are a ridiculously bad artifact of the past. We won't be using them for much longer anyway; they're limited to 2TB for 512-byte-sector drives (or 4K drives with 512-byte emulation).

Re:Interesting

[ScytheBlade1]

I disagree with the "but nothing that it unacceptable or even a need for concern" part. If copying the same image to the same disk where the only difference is where the partition begins -- by one sector difference -- will amount to a 2.6x decrease in speed, and where copying a large directory with many subdirectories amounts to a 3.2x decrease in speed... that should qualify as an unacceptable decrease in speed that warrants concern.

While a kernel tweak may help alleviate the issue, it is primarily an issue with our current (userspace) disk partitioning and formatting utilities. I'd also disagree with you on the point where the problem is the drive microcode; drives should do what they are told, and not guess on behalf of the instructions they are given what to do. Admittedly, the microcode tweak would be minor and largely trivial, but I'd rather not fix (primarily) userspace software problems in the kernel, nor the device firmware.

slashdot is not journalism

[SuperBanana]

should be an embarrassment of journalistic integrity.

Slashvertisements, basic English grammar and spelling problems, completely wrong summaries and titles...

...and you a)think that Slashdot is "journalism" and b)it's had integrity to lose in the first place?

I like Slashdot, but gimme a break...it's a user-driven blog which directs readers to existing stories (now often lagging behind the major news wires) with good categorization and semi-sophisticated commenting system, utilized by a larger commenter population. Not much more, and definitely not journalism.

Re:slashdot is not journalism

[Blakey Rat]

I'm with you, but on the other hand that doesn't mean they should just not give a shit about the quality of their end-product. We know from experience that they can edit and correct stories as corrections arise in the comments, but how often does that happen in practice? (Hardly ever.) Somewhere between a third and half of the stories posted here are either outright lies, or extremely misleading-- I may be exaggerating, but not by much-- and almost never are they corrected.

Look, any site that posts this article: http://tech.slashdot.org/article.pl?sid=09/02/16/2259257 without a single correct simply Does. Not. Give. A. Shit.

I don't think anybody's expecting the New York Times when they visit here, but some minimum level of competence would be nice. I don't fault anybody for complaining.

Re:I just bought one of these

[King Kwame Kilpatric]

The problem is that WD doesn't tell the system about the sector size.
dev/sdd:

Model=WDC WD15EARS-00Z5B1, FwRev=80.00A80, SerialNo=
Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=50
BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=16

It looks to me that this should *really* be fixed by WD with a firmware update

.

Solution: Instead of fdisk, call it as fdisk -H 224 -S 56 as per Theodore Tso's blog.

Re:if vista/win7 really do support this correctly.

[walshy007]

The real problem is that it is lying about it's sector size, it's reporting 512 bytes when it's using 4k, if it told linux it was using 4k everything would be fine and dandy.

Why does it lie about it's sector size when it doesn't need to? because if it didn't the drives would not work on windows XP at all. Which would not bode well for sales.

Once drives with 4k sectors arrive its up the individual maintainers of each affected tool (fdisk, et. al.) to update their code.

Kernel handles sector sizes, and could handle 4k sectors ages ago, but when the hardware reports something it tends to trust it, which is now apparent it shouldn't. (512 byte sectors being implemented as an emulation layer of sorts on these drives.. and enabled by default)

Drive lies and future fixes

[Sits]

There is an excellent thread talking about how recent (2.6.31+) linux kernels try to report the underlying hard drive architecture (found via the OSNews comments). Alas, it looks like some of these drives are not reporting this data correctly and thus automatic adjustment (at partitioning time) is not taking place. It looks like in the future rather than trying to do detection by reported capability fdisk (and hopefully gparted) will default to sectors of 1MiB if the topology can't be found by default (unless your media is small).

Additionally, I gather that recent Fedoras will try to adjust things like LVM to match larger sectors too. Hopefully whatever is laying out LVM will also be fixed too.

Coincidentally, it looks like Oracle have a very committed dev trying to make this stuff work by default...

Re:Interesting

[markus_baertschi]

About the microcode part. The drive pretends to be a 512byte drive, but internally is using 4k sectors and and claims to 'translate transparently'. I can understand that in a random-access scenario it it has to read-modify-write 2 sectors each time and performance suffers (2 additional reads and one additional write). But in a sequential access scenario, the penalty should be once per sequence/file, not once per sector. Here the microcode fails completely to make the best out of the suboptimal situation.

Re:Interesting

[hedwards]

That's true, but it's also true that having hardware lie to the OS isn't a great situation to be in. At the very least there should be some way of forcing it to be honest for the benefit of OSes that can handle the reality. A lot of the gunk and instability in computing comes from hardware that does things that are more appropriately done by software and vice versa.

Forcing users to optimize isn't inherently wrong, it's just that they shouldn't need to do it for things which are somewhat standard as a work around for weird hardware designs. And yes, I realize that the 4096byte sectors aren't being implemented arbitrarily.

Re:Partitions are obsolete

[hedwards]

Which is nice if you're wanting to ensure that you've got the lowest possible reliability and safety for your data. While you're at it, make sure you're using a striped non-redundant array of disks as well, best use at least 4 in the array, otherwise you might get some of your data back.

You've got it exactly backwards, people shouldn't be partitioning disks into one huge partition. They should be able to split things up a bit to keep rapidly changing directories from mostly static ones and to manage the risk of filesystem corruption destroying important files.

Re:if vista/win7 really do support this correctly.

[ArghBlarg]

I see it rather as an indictment against closed-source OSes, if XP turns out to be incompatible with these new drives and MS never releases a patch to add support. People will need to upgrade for no good reason to one of MS's new operating systems. People should not have to deal with a complete upheaval of their tested and true systems due to a small hardware change such as this.

I can imagine MS is quietly chuckling with glee to itself, if this issue becomes a deal-breaker for machines still running XP.

I was worried about this... and am still unclear

[bmajik]

I just got one of the 1TB 64mb WD drives that is known to be 4kb sector based.

Here is how it shows up in dmesg:
[ 3.420488] sd 1:0:0:0: [sdb] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB)

and here's what hdparm -I says:
ATA device, with non-removable media
Model Number: WDC WD10EARS-00Y5B1
Serial Number: WD-WCAV55227529
Firmware Revision: 80.00A80
Transport: Serial, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6
Standards:
Supported: 8 7 6 5
Likely used: 8
Configuration:
Logical max current
cylinders 16383 16383
heads 16 16
sectors/track 63 63
--
CHS current addressable sectors: 16514064
LBA user addressable sectors: 268435455
LBA48 user addressable sectors: 1953525168
Logical/Physical Sector size: 512 bytes
device size with M = 1024*1024: 953869 MBytes
device size with M = 1000*1000: 1000204 MBytes (1000 GB)
cache/buffer size = unknown
Capabilities:
LBA, IORDY(can be disabled)
Queue depth: 32
Standby timer values: spec'd by Standard, with device specific minimum
R/W multiple sector transfer: Max = 16 Current = 1
Recommended acoustic management value: 128, current value: 254
DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6
Cycle time: min=120ns recommended=120ns
PIO: pio0 pio1 pio2 pio3 pio4
Cycle time: no flow control=120ns IORDY flow control=120ns
Commands/features:
Enabled Supported:
* SMART feature set
Security Mode feature set
* Power Management feature set
* Write cache
* Look-ahead
* Host Protected Area feature set
* WRITE_BUFFER command
* READ_B

DragonFly's solution

[m.dillon]

We're adjusting our disklabel64 utility and kernel support to set the partition base offset such that it is physically aligned instead of slice-aligned, and we are using 32K alignment. That should fix the problem without having to mess around with fdisk.

The DragonFly 64-bit disklabel structure uses 64-bit byte offsets instead of sector addressing to specify everything. It ensures things are at least sector aligned but we wanted to make disk images more portable across devices with potentially different sector sizes. The HAMMER fs uses byte-granular addressing for the same reason, 16K aligned.

-Matt

partition table

[gd2shoe]

There won't be a partition table with his suggestion. The boot sector set aside by the filesystem will be the very first sector of the disk.

Poorly researched article.

[Vellmont]

The article represents one data point, for one particular way to install a drive, on one (un-named) version of Gentoo, on one particular model of a WD drive that had a bugzilla entry entered by the author all of 2 days ago. So this is supposed to be an indictment of all of Linux?

The author even mentions that Ubuntu has an option on parted that accomplishes the task properly. I'd be much more interested in an article that talks about how the default installer handles this task rather than concentrating on one particular expert tool that does so. It's still good to know that fdisk on his un-named Gentoo distribution does the wrong thing.. but this hardly means we should fire up the klaxon and declare "Linux not fully prepared for 4096 sector hard drives!". It's certainly interesting, but I'll withhold judgment until we actually know more about the implications of this across the entire spectrum of Linux distributions and the various 4096 sector HDs.

Re:Poorly researched article.

[Radtoo]

I agree with the headlines being grossly misleading. Linux does support 4k block sizes just fine. But this is not a distro-specific issue, so you are wrong, too.
This is simply a matter of fdisk from that version of util-linux-ng (which is clearly named in the article) trusting the hardware vendor to specify correct block sizes. The vendor did not. Thus fdisk does not end up with 4k block sizes, as happens for many programs. And only(?) parted apparently contains a workaround that detects the correct block size.

Its not that you can't use parted on Gentoo, though, it is just that in the world of user choices that is Gentoo, not everyone will be using that program or that particular option.

Re:Poorly researched article.

[Theovon]

I wrote the linked article.

I completely agree that the article is narrowly focused. VERY narrow. My objective was to demonstrate a problem and point out that Linux has not FULLY adapted. I didn't say Linux devs were idiots or that it would never be ready. I was trying to express the idea that Linux [distros in general but perhaps not all] is not QUITE ready for these drives, because not all the tools have fully adapted. Some tools make no mention of any problems in their man pages. Some (like parted's defaults) are even misleading if you mistakenly think that "track aligned" is a good thing.

And I was trying to do that in the very limited number of words I had available for a title.

Also, WD claimed that Linux is unaffected. Some distros probably are, but this could lead people to believe that the statement is universally true, which it isn't. Thus, my over-all objective is to educate people to the fact that if they don't know what they're doing, they can get this wrong. There are lots of mistakes I've made where I wished that someone had mentioned some critical fact on a how-to (like, don't use dmraid/fakeraid for RAID1 because reads aren't load-balanced; use mdraid instead). I've filed plenty of bug reports on such issues.

Re:Poorly researched article.

[Vellmont]

I can't over-emphasize the importance of titles in communication, especially with complex technical subject where there's a lot of evidence presented to support a conclusion. Your title colors the rest of the article and creates expectations about what you're trying to say. When people read articles (especially on the web) they scan through them trying to find the important parts. That's been demonstrated through eye-tracking studies multiple times.

Your title was very broad, but the evidence to support it was very narrow (as you admit yourself). Since your article only referenced Gentoo, and installing a drive after installation using fdisk, why not: "fdisk not ready for 4096 byte sector drives?" If you wanted to cover all of "linux" (whatever that is), why not research other distributions and see how they handle the job, installing the OS flat out on several distro's and see how they perform. If you didn't want to do the research, you could have written in an inquisitive style, i.e. "Is linux ready for 4096 byte sector drives?" and then presented your evidence and talked about how fdisk didn't do this, but parted worked a bit better, and how the drives reported 512 sectors but weren't, etc, but you've only tried Gentoo, and maybe others should try other distributions with other tools.

I think the experimental aspects you did were great, and I'm glad to know that some of the tools out there don't fully work with this particular 4096 byte sector drive. I just don't think you've done enough research to say much more than the problem affecs Gentoo, on these specific WD drives.

Re:if vista/win7 really do support this correctly.

[thisissilly]

It seems these drives need a new "don't lie to me, I can handle it" command, so OSes that don't have a problem with 4k size sectors can get the real info.

Re:Partitions are obsolete

[HiThere]

And then when you install a different distribution, you blow away your home directory. Sorry, bad idea. /home should be in a separate partition from the rest of the stuff..

Also, since I usually have several distributions installed at the same time, I have several partitions...but that's a less common problem.

A better solution would be to have a boot partition snuggled up against the MBR that automatically adapts so that the boot + MBR is an appropriate size, say 32 MB. (My current boot directory is 14MB, so that shouldn't be a problem. These aren't, after all, small drives, so it doesn't hurt to allocate a bit of extra space. Maybe even make that 64MB.)

Perhaps one could rearrange the system tables a bit so that the MBR was counted as a part of the /boot partition, and so was the partition table. They'd need to be an a position guaranteed by the OS, but that's not a real problem.

Note that what I'm proposing is a major redesign, so there's about zero chance of it being adopted. But it's a better choice than scrapping partitions, and probably has a better chance of being adopted.

Re:Partitions are obsolete

[Anonymous Coward]

Splitting a disk into multiple pseudo-disks makes sense in many situations, but the clunky legacy partition tables are only good for inter-OS compatibility. Otherwise LVM beats partitions in every respect. Now if only we could get a LVM solution that works in multiple operating systems...

a firmware update isn't realistic

[YesIAmAScript]

I'll get to why in a second, but first:

RawCHS hasn't meant anything in a decade. The largest drive you can describe with CHS is 8GB.

Track size hasn't meant anything in even longer than that. When drives went to zone bit recording (ZBR), the number of sectors per track became variable. This happened in about 1989.

The sector size does mean something, but it is the actual sector size, not the sector "grouping" size. If the drive reported a sector size of 4K, then it would expect that the host understand that sectors are actually 4K in size, not 512B in size. But really no major OS supports this, they all expect 512B sectors. That's why these drives internally use one sector size and show another size to the host. And there is no way in the ATA specification for devices to indicate their internal sector size when they are presenting a different external sector size.

So this won't be fixed with a firmware update, unless Vista, 7 and every other major OS is fixed to actually support large sectors presented to the host. Then the drive could be firmware updated to report the large sector size to the host. And the drive would then be completely unusable under any earlier OS or with any USB or Fireware adapter.

whoops, one thing about RawCHS

[YesIAmAScript]

I forgot, there is one thing RawCHS nowadays. That is that there is no proper spec for how to know if a partition in an MBR (fdisk) partition table is a valid partition. So there are heuristics that are applied to the entries to guess if they are real or to be ignored as empty. One of the heuristics that some software uses is to ignore all partition entries that don't begin on a cylinder boundary. To be on a cylinder boundary, the partition has to start on a sector number that is a multiple of the number of sectors (S in CHS) in order to be valid. And since all drives 8GB or greater present an S of 63, that is why the first partition on an MBR disk has always started at sector 63, which makes it unaligned when the internal sector size is 4K (8 internal sectors).

Windows before 2000 checks the CHS alignment of MBR entries and ignores any partition entries that don't start on a multiple of S. So all disks out there are misaligned. With Windows 2000 or later, you can start the partition on any boundary you want.

Western Digital has a jumper you can put on the drive that adds 1 to all access requests, making all those misaligned first partitions aligned. But it'll also make any aligned partitions misaligned. So the real answer is just to layout your disk different. I would recommend using GUID disk partitioning instead of MBR anyway, because MBR doesn't work for >2TB drives. And GUID doesn't have any weird alignment requirements (and doesn't have any knowledge of CHS).

Re:whoops, one thing about RawCHS

[hpa]

The original reason for aligning to track boundaries (a track is a cylinder-head pair) is that the first four sectors of MS-DOS' IO.SYS (IBMBIO.SYS) had to be contiguous and on a single track.