RAID 1 Question on Dell SC 1420 Poweredge
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From: JTeel on 9 Jun 2010 21:49 I have a RAID 1 array on a Poweredge SC 1420 that recently had on drive fail. The controller is an onboard CERC SATA 1.5/2s. I have read that it is possible to upgrade to a different controller using the same disks without loosing data providing the new controller is of the same family since the RAID configuration is stored on the HD. What controllers would be considered "of the same family" as the CERC SATA 1.5/2s? I would like to use the current functional drive along with a new larger drive and after the new drive has been rebuilt replace the smaller drive with a new drive and end up with two fresh drives. The current drive is also low on c:/ partition space and I need to expand that as well. I would appreciate any suggestions that you may have with this project. This is a family server and only has five users on it. Thanks for your input. Jeff
From: Cliff Galiher - MVP on 10 Jun 2010 23:41 Truthfully? I wouldn't bother. SATA drives don't handle RAID very well regardless of configuration. If you are going to spend money upgrading your RAID config, go SAS. Otherwise you are just spending good money after bad. -- Cliff Galiher Microsoft has opened the Small Business Server forum on Technet! Check it out! http://social.technet.microsoft.com/Forums/en-us/smallbusinessserver/threads Addicted to newsgroups? Read about the NNTP Bridge for MS Forums. "JTeel" <jdteel(a)sugardog.remove.com> wrote in message news:e$dBd8DCLHA.5464(a)TK2MSFTNGP05.phx.gbl... > I have a RAID 1 array on a Poweredge SC 1420 that recently had on drive > fail. The controller is an onboard CERC SATA 1.5/2s. I have read that it > is possible to upgrade to a different controller using the same disks > without loosing data providing the new controller is of the same family > since the RAID configuration is stored on the HD. What controllers would > be considered "of the same family" as the CERC SATA 1.5/2s? I would like > to use the current functional drive along with a new larger drive and > after the new drive has been rebuilt replace the smaller drive with a new > drive and end up with two fresh drives. The current drive is also low on > c:/ partition space and I need to expand that as well. I would appreciate > any suggestions that you may have with this project. This is a family > server and only has five users on it. > > Thanks for your input. > > Jeff >
From: Leythos on 11 Jun 2010 07:38 In article <0B739B27-1EA9-4EBD-8414-C3BE56EC973A(a)microsoft.com>, cgaliher(a)gmail.com says... > Truthfully? I wouldn't bother. SATA drives don't handle RAID very well > regardless of configuration. If you are going to spend money upgrading your > RAID config, go SAS. Otherwise you are just spending good money after bad. > There is no difference in how they "Handle" RAID, they don't know the difference at all. The issue is "Performance" alone. If you had a 8 drive SATA-II RAID 5 setup, it would perform better in reads/writes than a 3 drive SAS/SCSI RAID 5 setup, provided you used business class drives instead of the home system class drives. -- You can't trust your best friends, your five senses, only the little voice inside you that most civilians don't even hear -- Listen to that. Trust yourself. spam999free(a)rrohio.com (remove 999 for proper email address)
From: Cliff Galiher - MVP on 12 Jun 2010 01:50 Without turning this into too much of an inside-baseball type of conversation, that is simply not true. SAS is also more reliable for many reasons, but off the top of my head, here are a few: SAS is full-duplex, SATA is half-duplex. This has had demonstratable effects when a RAID controller has to rely on its battery after a power outage and power restore to finish playing the cached commands. SAS generally uses tagged command queueing. SATA uses native command queueing. For reliability, lab tests have shown tagged command queueing to be more reliable. SAS hardware, including most RAID backplanes, support multipath I/O. A failure on a backplane properly supporting SAS can be bypassed and the array will operate in a degraded state. A failure on a backplane running SATA drives effects all drives at the point of failure *and* beyond, which in RAID5 can be significant and cause data loss. SAS uses the SCSI command set (hence the name Serial Attached SCSI) which is *far* more robust in error recovery than SATA's reliance on ATA SMART commands. No, SAS has real error-recovery benefits beyond just performance that make SATA unsuitable in any serious RAID configuration. -- Cliff Galiher Microsoft has opened the Small Business Server forum on Technet! Check it out! http://social.technet.microsoft.com/Forums/en-us/smallbusinessserver/threads Addicted to newsgroups? Read about the NNTP Bridge for MS Forums. "Leythos" <spam999free(a)rrohio.com> wrote in message news:MPG.267bea5060dcbb2a98a3d5(a)us.news.astraweb.com... > In article <0B739B27-1EA9-4EBD-8414-C3BE56EC973A(a)microsoft.com>, > cgaliher(a)gmail.com says... >> Truthfully? I wouldn't bother. SATA drives don't handle RAID very well >> regardless of configuration. If you are going to spend money upgrading >> your >> RAID config, go SAS. Otherwise you are just spending good money after >> bad. >> > > There is no difference in how they "Handle" RAID, they don't know the > difference at all. The issue is "Performance" alone. > > If you had a 8 drive SATA-II RAID 5 setup, it would perform better in > reads/writes than a 3 drive SAS/SCSI RAID 5 setup, provided you used > business class drives instead of the home system class drives. > > -- > You can't trust your best friends, your five senses, only the little > voice inside you that most civilians don't even hear -- Listen to that. > Trust yourself. > spam999free(a)rrohio.com (remove 999 for proper email address)
From: Leythos on 12 Jun 2010 12:31
In article <61E010EC-FB2C-490B-A08C-81CE49A236C5(a)microsoft.com>, cgaliher(a)gmail.com says... > > Without turning this into too much of an inside-baseball type of > conversation, that is simply not true. SAS is also more reliable for many > reasons, but off the top of my head, here are a few: > > SAS is full-duplex, SATA is half-duplex. This has had demonstratable effects > when a RAID controller has to rely on its battery after a power outage and > power restore to finish playing the cached commands. Duplex has nothing to do with reliability if there isn't a failure. Battery is also an issue, many SATA controllers have a battery option. > SAS generally uses tagged command queueing. SATA uses native command > queueing. For reliability, lab tests have shown tagged command queueing to > be more reliable. More reliable? When, in a lab induced failure mode that can't be duplicated by 99.99999% of real world conditions? > SAS hardware, including most RAID backplanes, support multipath I/O. A > failure on a backplane properly supporting SAS can be bypassed and the array > will operate in a degraded state. A failure on a backplane running SATA > drives effects all drives at the point of failure *and* beyond, which in > RAID5 can be significant and cause data loss. Sorry to say, but if you have a failure of a typical MOTHERBOARD back- plane, like those on a cheap server board, you have a lot more problems than just RAID - in the real world. As for SAS operating in a degraded state with a backplane failure, not without a redundant backplane, and I've never had "part" of a backplane fail on any DELL or IBM server, it's always been an all or nothing type failure. Since the OS would normally be on a RAID-1, this isn't much of an issue for a typical cheap SATA solution, since you're going to have a RAID-1 for the O/S and then a RAID-1 or RAID-5 for the data - the O/S array will operate in non-RAID and you can restore the RAID-5 array from backup, the same as you would from a failed SAS backplane - the difference is that the SAS system is most likely to have the RAID-1 OS and RAID-5 on the same backplane or controller, where a cheap server would have a controller for the RAID-1 and another controller for the RAID-5. > > SAS uses the SCSI command set (hence the name Serial Attached SCSI) which is > *far* more robust in error recovery than SATA's reliance on ATA SMART > commands. > > No, SAS has real error-recovery benefits beyond just performance that make > SATA unsuitable in any serious RAID configuration. I'm sorry to inform you that in a real-world setup, there is little difference, other than I/O performance. I say this from experience with hundreds of SATA and SAS arrays across everything from mom-pop servers to $35K IBM servers with a dozen drives, and $24K Dell Servers with 8 Drives, SAS/SCSI, SATA.... The real issue is I/O performance. The drives, if you buy commercial drives, last just as long. You do know that there are very high quality IDE and SATA RAID controllers that allow HOT-SWAP, Battery Backup, predictive failure, multiple-online hot spares.... -- You can't trust your best friends, your five senses, only the little voice inside you that most civilians don't even hear -- Listen to that. Trust yourself. spam999free(a)rrohio.com (remove 999 for proper email address) |