Slashdot Mirror
WD Explains Its Windows-Only Software-Based SSHD Tech
crookedvulture writes "Seagate and Toshiba both offer hybrid hard drives that manage their built-in flash caches entirely in firmware. WD has taken a different approach with its Black SSHD, which instead uses driver software to govern its NAND cache. The driver works with the operating system to determine what to store in the flash. Unfortunately, it's Windows-only. You can choose between two drivers, though. WD has developed one of its own, and Intel will offer a separate driver attached to its upcoming Haswell platform. While WD remains tight-lipped on the speed of the Black's mechanical portion, it's confirmed that the flash is provided by a customized SanDisk iSSD embedded on the drive. The iSSD and mechanical drive connect to each other and to the host system through a Serial ATA bridge chip, making the SSHD look more like a highly integrated dual-drive solution than a single, standalone device. With Intel supporting this approach, the next generation of hybrid drives appears destined to be software-based."
Yeah, that was a nightmare!
Linux already supports SSD-HDD caching with normal drives so if anything, it will probably already work or work with little changes. Otherwise, just pick up a tiny SSD and ignore this solution. http://bcache.evilpiepirate.org/
Nice troll, btw.
It isn't clear, exactly, from TFA what the drive will look like when you plug it in. Both components(the HDD and the SSD) apparently can function as SATA peripherals; but they are both behind some sort of bridge chip, type unspecified.
If the 'bridge chip' is just a reasonably generic SATA port multiplier, then an unsupported OS, or Windows without the driver, will just see two drives, the larger mechanical one and the smaller flash one. This would leave the way open for any OS with SATA and AHCI support to do whatever it prefers to get the best performance(on Linux, I assume that'd be at the filesystem level, with something like btrfs)
If the 'bridge chip' is some sort of proprietary oddity, and the vendor driver is required to even communicate with the flash portion(presumably at least some part of the drive will be visible as a normal SATA device, or booting without specific BIOS support would be a problem...), then that's pretty much worthless.
The iSSD and mechanical drive connect to
I believe I speak for the majority here when I say.... D'ARGH! KILL IT WITH FIRE NOW! This is yet another pathetic attempt by WD to marry it's crappy line of mechanical drives to SSDs in order to stretch their relevance out a little bit longer and keep them from having to retool their assembly lines and such to produce SSDs exclusively. Weeeell, good for you guys. But as my father would say: "Shit or get off the pot." Either switch to SSDs, and eat the cost, or stick with mechanical drives because they're cheap. But don't waffle and try to do both; You're getting the worst of both worlds then.
#fuckbeta #iamslashdot #dicemustdie
... in all the big Fortune double-digits, that have their data centers overflowing with Linux servers.
The worst part of this, is that when WD goes bankrupt, as a result of this brilliant business strategy, there'll be even less competition in the HD market, which always means higher prices.
As an end-user, I'm NOT going to put up with a solution like this.
Even if it somehow performs better than current hybrid drives.
Even though most of my work is done on a Windows platform.
Hybrid drives are already a big compromise for minute gains.
Tying it to an OS choice?
NO FUCKING THANKS WESTERN DIGITAL!
In a budget situation I'd rather just put up with a competitor's hybrid or a plain old mechanical disk.
In a performance situation I'd rather just spring the extra cash for a real SSD. Better returns and more flexible.
Chas - The one, the only.
THANK GOD!!!
WD has taken a different approach with its Black SSHD
They'll have a lot more explaining to do, once some hacker, cracks the SSH password, starts pwning WD disk drives, and they begin to spew forth spam... :)
And its worth reminding people, that Windows already caches stuff in RAM, if you had 24GB of ram then it would be a lot faster cached, and the only gain with these drives is on startup and then not by much (since Windows arranges the disk so the common items are close together ready for boot).
So WD simply remind everyone why hard disk makers are struggling to remain relevant.
Uh, okay, whatever.
Guess I won't be buying one. Best of luck to those that do.
Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.
At under $250 for a 256 Gig SSD, why would anyone buy a combination drive anymore? This would be like GM announcing that their next flagship green vehicle is powered by 150 horses.
The dm-cache device mapper target was added to the kernel in Linux 3.9. bcache is apparently on track for 3.10
I see that you don't really understand what Apple's Fusion Drive really is. In Intel's SRT the SSD drive acts like a cache for the HDD. I hope I don't need to explain what a disk cache is and how it works. In the Fusion Drive on the other hand both drives appear as a single logical volume with the space of both drives combined and the OS decides which files get stored on the SSD and which on the HDD. From the Ars Technica article I quoted:
In a caching solution, like Intel's, files live on the hard disk drive and are temporarily mirrored to the SSD cache as needed. In an enterprise auto-tiering situation, and with Fusion Drive, the data is actually moved from one tier to another, rather than only being temporarily cached there.
Those are two very different approaches.
Think secure boot. If the 'bridge chip' has a key, that only the trusted driver can supply, then with UEFI and "secure boot", they have just locked down the machine to windows only.
You are being MICROattacked, from various angles, in a SOFT manner.
The nice thing about Seagate HHDDs or SSHDs or whatever the companies what to call them now is that they just work. You drop it in a system, it works like a normal drive but faster. The flash works like cache on a RAID controller or the like. It just speeds things up.
With this, there's mucking about. Even if you could use it as separate drives, why would you want to? If I want to to just some small SSD storage and larger magnetic, I can. In fact I do. In my laptop I have a SSD for OS and apps and an HDD (actually one of Seagate's hybrids) for media and samples. My desktop is the same but more and larger drives.
It just seems silly to me. An all hardware approach seems much better and clearly doesn't cost that much as Seagate's drives are not expensive.
Honestly i never looked too deep into it. I saw Fusion, saw what it did on the surface, on Intel hardware and assumed it was SRT. Thats what i get for assuming. thanks.
Good-bye
Do it in OS-agnostic firmware, you lazy shits.
Well, you can have any color you like, so long as it's black.
It's probability because there is no set life just a chance of failure. For example, with tossing one coin you have a 50% chance of getting one head and with two coins you have a greater chance of getting at least one head. With two components the low risk of failure per year gives a very long time for each separately for the time when half are expected to fail. Combine them and the chance for either of them to fail is combined so the time when 50% of the complete systems are expected to have some sort of failure is reduced to a lower time than either of the parts. :)
That's what you get for saying "that's not how it works" without stopping to think about it
In my computer, I have a Crucial M4 SSD for the boot drive and the more speed fasterness "crucial" apps. Then I have a WD Black terabyte drive for all the shit that doesn't need to be maximum possible speed.
Sometimes, I change my mind what needs to be faster than what is not at the forefront of my mission anymore. That's when I move my files around manually. Mind you, these are usually 8 - 20 GB of files or whatnot. This type of operation I do not want an un-brained background process to be performing at random times. If it picked the wrong time, I might drop FPS in an online match that was worth so many imaginary dollars to nobody at that precise moment...
Remember those great Intel software-based modems back in 1993 that Intel had for Windows 3.1 that weren't supported by any operating system afterwards?
Remember how Intel sold that line of business and left us all hanging? Yeah.
Software based hardware like this is destined to be a one-trick pony. Use it in one system, and then it's stuck on that operating system for the duration. You'll be left in the lurch when the next version of you OS is released.
Go ahead and line-up to get screwed by WD and Intel. I'll skip this round of fleecing.
No, they're quite different. Fusion Drive gives you the capacity of both drives, doesn't have a 64GB SSD size limit but you are guaranteed to lose data if the SSD dies. Intel SRT in enhanced mode protects data against SSD failure but not HDD failure. Fusion Drive isn't a cache, it's a tier.
With how much straight SSD prices have dropped over the past few years, I don't even really see much need for a hybrid drive. In 2011 I bought a 60gb ssd for $95 ($1.58/gb). Today, I can buy a better performing 500gb ssd for $350 ($0.7/gb).
Since OSX and Linux already do this, maybe only Windows needed a driver.
Even if I ran windows I can't see having a driver for my hard drive. It should just work no matter what OS I am running. Sad and stupid. That's okay though as for me I don't think the hybrid is the way to go. SSD for the OS and external platter type for storage. Like most compromises this seems like the worst of both worlds.
Yeah, a drive that depends on any kind of OS besides the bare metal firmware on the board to which it is attached makes me uneasy. There are just so many more answers to the "what could possibly go wrong" question.
... whatever
Um, no, not really. While Seagate doesn't explain their caching strategy, my guess is that unlike things like bcache, which cache at the block level, the seagate probably caches at the logical file level, which would explain why it's Windows only, they only implemented their algorithm for NTFS. My guess is they broke with tradition and implemented a disk that is aware of the logical layout of the files on it, instead of one that simply manages blocks(with file metadata just being another one of those blocks)
File level caching has a lot of advantages, for starters there tend to be a lot fewer blocks than their are files, meaning that the overhead imposed by the caching algorithm is a lot lower(flashcache for instance uses 500 megs of memory per TB of storage IIRC). Furthermore, by caching at the file level you can apply heuristic rules like not caching movie or music files, where performance is very unlikely to be critical etc.
Of course this all comes at a cost, having the disk actually know about the logical layout of the file system does break a lot of conventions and introduces a large # of potential issues....Trying to upgrade the file system on one of these things is probably not very pretty.
Monstar L
Nice post, but the article is about WD, not Seagate....
Similar question: Which would you rather have: software RAID or hardware RAID? On Linux, software RAID is usually faster, cheaper, more reliable, less buggy & fuller featured.
So yes, I'd prefer the drivers in my operating system rather than buried in some inaccessible firmware somewhere.