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Chipset Serial ATA RAID Performance Exposed
TheRaindog writes "Serial ATA RAID has become a common check-box feature for new motherboards, but The Tech Report's chipset Serial ATA and RAID comparison reveals that the performance of Intel, NVIDIA, SiS, and VIA's SATA RAID implementations can be anything but common. There are distinct and sometimes alarming performance differences between each chipset's Serial ATA and RAID implementations. It's also interesting to see performance scale from single-drive configurations to multi-disk arrays, which don't offer as much of a performance gain in day-to-day applications as one might expect."
Does the raid driver typically allow two independent seeks on the seperate drives with mirroring enabled? I would expect this to significantly improve things like boot times as most of the time is spent seeking for new data. I would have expected a 50% drop in seek. If they don't do independent seeks, why the hell not?
>[...]for the boot partition.
I boot once a day. I'm typically in the bathroom while the machine goes up. Seems like a darn waste to put the boot partition on a RAID-0.
I run all my games off a RAID-1, and it does help loading time in most games. Game resources are ever-increasing in size.
..been a sore spot with me. Most users do a RAID 0 setup so their cool rig is hottie fast. Truth is, I can't see much real world performance difference. For my money, a large SATA drive and an external FireWire for backups is the way to go. Simple setup, no worries about drive failure and losing data, and still fast enough for UT2004.
Don't be a looter...and yes, I know that it's spelled with an "A" instead of an "E".
Good deal, ONLY if the manufacturors are being honest with drive spec. Several coworkers that used to work for Quantum have indicate that the actual drive mechanism used in SCSI and ATA drives frequently shares common mechanical parts (platters, spindle motors, etc.) Their differences are ENTIRELY artifical. SCSI drive spec at times looked "better" in part because of the firmware difference and cheating on SPEC; for instance seek time for SCSI drive are computed differently to create the illusion that somehow SCSI drives seek faster...
ELOI, ELOI, LAMA SABACHTHANI!?
So why make a RAID?
They are not talking about mirroring (RAID 1) exclusively. They are talking about RAID 0 so people can stripe drives and achieve considerable performance increases.
As for me, I have an 8-channel IDE raid card with 8 x 120GB drives, hardware RAID 5, and in 24 months have blown oh about 4 drives (3 on the same channel til I found a faulty cable)... I have really appreciated the 860GB array having fault tolerance. And yes, I do some backups of critical data, but I can't afford the storage required for regular full backups.
For the past 3 years I've had a RAID array set up on my home computer. It is a RAID 5 array with four 18GB Seagate X15 hard drives on an AcceleRAID 170 PCI card. I'm on the computer several hours a day during which time I play various video games, program in visual studio, and transfer a bunch of MP3 sized files and very large video files (~2GB). From my experience, the RAID 5 is definitely faster in some tasks than a high-performance ATA drive (like game loads) but for the types of activities I'm doing the expense of the SCSI drives and the noise they generate is more costly to me than the (perceived) slight speed disadvantage of a single disk serial ATA drive.
Don't get me wrong, the RAID 5 array is sweet and certainly amps up geek appeal, but I don't have enough friends who know what the hell a RAID array is to really impressive them.
-Berylium
I know that on my Mac - if i slap in an additional identical HD to the one that shipped with it...
... setup... is that that many people would would bennifit from such technology will NEVER USE IT because its inaccessable to them.
1. i go to Disk Utility (standard issue with OS X)
2. select the two blank drives (with the mouse, clicking on them)
3. click "RAID 1" or "RAID 0"
4. repartition them with a GUI (not required)
then the RAID is mounted automatically on the desktop, ready for use. period. end of issue.
that's basically 4 steps - none of which require any "understanding" beyond your average emailer's brainpower. (i'm not including the "Are you sure?" dialogs - those don't count as steps)
its things like this test that bake my brain... and why Mac users are rabidly so asshole when it comes to stuff like this.
All this geek speek about a few kbps difference between the various choices out there - but when it comes down to it - its a motherfscker to try to set it up in windows and, unfortunately, Linux, which takes the cake for scoring highest on the "WTF Does That Mean?"-o-meter for disk partitioning.
And the PROBLEM with all the difficulties in setup of such a
How useful is that? its not.
Its a classic GSFPREZ Axiom On system Performance...
"A Mac Plus will always outperform a Pentium 100 when the Pentium is experiencing an IRQ conflict between the video card and the modem card"
while i KNOW that IRQ issues are of the past - the idea that a superfast desktop comptuer that is difficult to get functioning is no gawddamned use - and by definition is an anchor compared to a Model-T Macintosh... at least the Model T moves, whereas anchors don't.
all the speed and power in the world is useless to those who are more interesed in DOING work with their computer, than WORKING ON the computer to get it functional.
My RAID on my G5 may be slower than yours - but it took me about 2 minutes - total, including the installation of the 2nd card drive but most importantly...
(Mitch Hedberg =+5) this thing is useful, motherfscker!(/mitch)
laugh, its funny.
guns kill people like spoons make Rosie O'Donnell fat.
Since every SATA raid controller (bar the i960 based one from adaptec) is done using software, I reckon that what is actually benchmarked here is how optimum the drivers are, not the hardware performance. Besides (I'm guessing, as I only read the conclusions page) that each of these interfaces is connected off of a crummy 32 bit 33MHz PCI interface... That's the real killer right there.
I have a Dell PowerEdge in the back room with 2 15k scsi drives running linux and raid 0 - with hdparm -t this thing gets 125-128 mb/sec! The HD interface on that machine is definitely hung off of a PCI-E interface or something better; as the maximum theoretical transfer rate of PCI is about 33*32 million bits per second or 132 megabytes per second.
What would be really nice is if the filesystem was put on the i960 based adaptec card...
"Of course, for all its prowess, I'm still a little troubled that the ICH5R's RAID 1 arrays crashed out of IOMeter under our highest load level. A load of 256 outstanding IOs is quite a bit beyond what most desktops and workstations will encounter, but it's well within the realm of possibility for servers" Can anyone confirm or deny that this occurs in real world settings? Its definitely troubling that the crash condition was consistent, but I am suspicious that it was simply an incompatibility between the benchmarking tool and the raid controller. Does someone know more? Jeff
For me, personally, transfer rates are #1, seek times are #2.
And for the record, this article only cements in my mind that SATA is seriously no better than IDE, just a faster version of IDE, with all its inherent problems.
Firewire is another one that's basically DOA for HDs. SCSI really is your only solution, especially if you're looking for RAID performance. (Of course, that's not your normal consumer purchase, but I have 3 SCSI RAIDed systems, so I'm not your normal consumer;)
The cesspool just got a check and balance.
Sustainable speeds. From the pictures in the article, you can see that drives that may have the highest max speed don't always have the highest average speed.
:)
But then you have to hook your drives to a controller. And controllers have the read/write & reliability factors that hard drives do AND they also have CPU utilization.
Ideally, you'll want hard drives with fast read/writes and high reliability hooked to a controller that does fast read/writes and has high reliability AND very low CPU utilization.
But if you're just looking at hard drives, you're correct in your statement.
But for best utilization of the hard drive, you at least have to look at the controller, also.
And cables.
Anyone know where to find these kinds of benchmarks for Linux software RAID systems? I almost always set up 2-disk RAID 0 and 1 on my Linux boxes, and haven't run into as many problems as they describe here. The performance scales up fairly linearly.
I've always wanted to compare the Linux SW RAID to the HW RAID controllers, to see if it's worth the extra CPU cycles. My guess is that it is, but it'd be great to have some numbers to back this up.
I suppose I could do it myself with hdparm and bonnie++ if it really came down to it, though... any interest in that?
No, you're referring to striping, not mirroring. In fact, mirroring shouldn't give you any speedup in transfer rate at all -- since the data is mirrored to both drives, you're writing 20MB each to both drives.
I'm talking about reading from the drives. Given a mirror of two identical drives, you have your choice of which to read from. This will not cause delays. It will speed things up. It is speedier than striping for reads overall, because you have your choice of which spindle to read from, and there is no stripe width to bound your maximum I/O size.
I think earlier on in this topic someone posted an incredulous message on how very confused people seem to be about what RAID is and how it actually works in theory and practice. I think he's right, and suggest you and others do a little research before drawing such conclusions as you have here.