On 03/01/2012 09:00 AM, Mark Roth wrote:
Miguel Medalha wrote:
A few months ago I had an enormous amount of grief trying to understand why a RAID array in a new server kept getting corrupted and suddenly changing configuration. After a lot of despair and head scratching it turned out to be the SATA cables. This was a rack server from Asus with a SATA backplane. The cables, made by Foxconn, came pre-installed.
After I replaced the SATA cables with new ones, all problems were gone and the array is now rock solid.
Thanks for this info, Miguel.
<snip> > > As an additional information, I quote from the Caviar Black range > > datasheet: > > > > "Desktop / Consumer RAID Environments - WD Caviar Black Hard Drives are > > tested and recommended for use in consumer-type RAID applications > > (RAID-0 /RAID-1). > > - Business Critical RAID Environments ? WD Caviar Black Hard Drives are > > not recommended for and are not warranted for use in RAID environments > > utilizing Enterprise HBAs and/or expanders and in multi-bay chassis, as > > they are not designed for, nor tested in, these specific types of RAID > > applications. For all Business Critical RAID applications, please > > consider WD?s Enterprise Hard Drives that are specifically designed with > > RAID-specific, time-limited error recovery (TLER), are tested > > extensively in 24x7 RAID applications, and include features like > > enhanced RAFF technology and thermal extended burn-in testing." Wonderful... NOT. We've got a number of Caviar Green, so I looked up its datasheet... and it says the same.
That rebuild of my system at home? I think I'll look at commercial grade drives....
mark
Interesting thread ... I have had problems with SATA cables in the past, and prefer those with the little metal latches. The problem is that you can't easily tell by looking at the connectors whether or not they're flakey.
I've had positive experience with Caviar Black and Scorpio Black drives.
The WD Green and Blue drives are built more cheaply than the Blacks (which have close to enterprise-grade construction). The dealer I buy drives from has told me that the Blacks have far lower return/defect rates. Of the approximately 30 2TB Blacks I have in RAID-6 service, I've only experienced two failures, which were handled quickly by the WD warranty program. It's interesting to note that while all the drive manufacturers are going back to 1 or 2-year warranties, the WD Black series remains at 5 years.
A friend of mine has had a couple of strange problems with the RE (RAID) series of Caviars, which utilize the same mechanics as the non-RE Blacks. For software RAID, I would recommend that you stick with the non-RE versions because of differences in the firmware.
It has come down to me buying *only* WD Black-series drives and nothing else. If I could afford them, I'd consider enterprise-grade drives.
Having said that, I have a pair of 1TB Green drives in RAID-1 for the TimeMachine backups on my Mac, and they've been spinning 24x7 non-stop for 3 years without failure. I'm almost afraid to switch them off.
Now, if WD can just get their post-flood production back in gear so prices can drop. My 2c, FWIW :-)
Chuck
A friend of mine has had a couple of strange problems with the RE (RAID) series of Caviars, which utilize the same mechanics as the non-RE Blacks. For software RAID, I would recommend that you stick with the non-RE versions because of differences in the firmware.
I would recommend the opposite. If you use a RAID at all, the 'raid edition' or 'enterprise' or whatever drives give you significantly better uptime. (Now, is that worth the additional cost? that depends on your application. They are rather more expensive, and for some applications, a few hours of downtime every few years isn't a big deal, in which case, by all means use the WD Black drives; you save a bunch of money, and they are about as fast. I use consumer drives in my own desktops, because nobody but me cares if the thing is working, and I only care when I'm physically nearby and can fix the damn thing if it's broken.)
I have tried /very/ hard to get some sort of consumer-grade drive working in a raid, hardware or software. I've tried on the order of 50 drives, many of them WD black, and many of those with the WDTLER.exe hack set. I still have a few of these in production, but whenever I get half a chance, I swap out the consumer-grade drives for enterprise or raid-edition drives, even at today's ridiculous drive prices. I RMA the bad consumer drives and have been giving them away to friends and people that have done me favors. (If anyone wants to arrange a 'many consumer drives for few enterprise drives' swap, let me know.)
The WD blacks mostly work, and they perform well. The problem is that they don't fail reliably.
The other problem I notice is that it's very rare to see a system with 1 raid edition drive that is significantly slower than others of the same model in the same system. It's fairly common to see this with consumer drives.
I mean, everything should be RAID. soft/hard/whatever- spinning rust without redundancy is just a bad idea, unless you are using it as 'really slow ram' kind of scratch space, and even then, redundancy is a good idea unless you have auto provisioning down so well that rebuilding a box is no additional work. My auto provisioning is not that good yet, so I RAID even data I don't care about, because I don't want to have to bother rebuilding the system when the drive fails. So when a drive has problems, I want it to fail and let the RAID system handle it.
The problem with consumer grade drives (and I've seen this with WD Black consumer drives, both with WDTLER.EXE and without) is that often, before they fail? they get really, really slow, sometimes to the point of completely or nearly completely hanging the raid.
To be clear, similar things occasionally happen with 'enterprise' or 'raid edition' drives too, but it's very rare and usually not as bad. I can count the number of times this has happened to me ever without taking off my shoes. Just yesterday I had a WD RE4 500gb drive (a fairly nice 'enterprise' drive- most of my current drives are similar) fail in such a way that my 4 disk raid10 dropped from it's normal 100+MB/sec sequential throughput down below 30Mb/sec, and latency went through the roof. The box was nigh unusable until I failed that drive out. But, it's very rare that with 'enterprise' drives the whole thing completely freezes up, and this way, at least I could log in, figure out what was up and fail the bad drive.
With consumer grade drives (Including the wd blacks with WDTLER) it's pretty common for the whole raid to completely freeze.
It isn't a problem with software raid alone; I've seen it with 3ware and LSI RAID cards, too. (In one test with a known bad but not reporting it drive, the 3ware didn't freeze up quite as hard. It kept 'retrying' the bad disk, then you had a second or two of access to the RAID, then it went back to 'retrying' and the RAID was frozen for a few seconds, etc...)
I mean, my total fleet is under a thousand drives, and I don't have a good inventory system tracking errors, but I only have a few consumer-grade drives left in production, but it's still fairly common for a bad consumer drive to hang up an old server and set off my pager in the middle of the night, 'cause I/O has hung on one of the servers. When a raid edition/enterprise drive fails, I get an email, but I can deal with that in the morning. The RAID continues chugging along as long as I have enough good drives left.
-
Chuck Munro -
Luke S. Crawford