"Bryan J. Smith" wrote:
Had you used the 3Ware's intelligent hardware RAID, it would have hidden the drive disconnect from the system. You'd see a log entry on the failure, and that the array was in a "downgraded" state.
Instead, you're using software RAID, and it's up to the kernel to not panic on itself because a disk is no longer available. The problem isn't the 3Ware controller, it's the software RAID logic in the kernel.
<smile>As much as I hate to agree with Bryan </smile>, this has been our experience also. We have many TB of disk running with 3ware controllers. We used to use software RAID, because at that time we found 3ware's tools to notify us of disk/array problems unusable. During that time, we could always tell when a disk failed, because we would have a crashed server. The data would always be there after we rebooted, but a reboot was necessary. A few years ago we migrated everything to 3ware hardware RAID, and now we rely on our alert system, instead of our users, to tell us when a drive fails.
Dave Thompson The University of Wisconsin - Madison
David Thompson thomas@cs.wisc.edu wrote:
<smile>As much as I hate to agree with Bryan </smile>, this has been our experience also.
Oh boy, now you're a "marked man" with regards to others. ;->
We have many TB of disk running with 3ware controllers. We
used to use software RAID, because at that time we found 3ware's tools to notify us of disk/array problems unusable.
Hmmm, which ones/kernel combinations?
You must also be sure to match your firmware + driver + 3DM version. That's pretty easy with the 7000/8000 series, because the kernels have had the latest 3w-xxxx driver for a good 18+ months now (maybe close to 2 years).
That's the only issue I've ever seen -- people using different kernel driver versions to their firmware and/or user-space software. While that administration headache plagues every hardware RAID card, but it is easily trackable.
Now there was a change with the 2.6 kernel IOCTL that no longer works with some of the older 3DM releases. But the newer 3DM2 for the 9000 series works with the older 7000/8000 series, no issues. That's what I use today.
I've had to have 1 byte go due to a 3Ware card in almost 6 years of deployments, although I did have 2 ATA disks fail within the span of 18 hours (in the middle of a rebuild). Fortunately I was able to "knock" one of the ATA drives to get it to spindle and then finish the rebuild of one drive.
During that time, we could always tell when a disk failed, because we would have a crashed server.
Because you have to use something else to "trap" the failed disk.
The MD suite and kernel drivers do _not_. There is the continuing farce that the 3Ware in JBOD mode does, as well as allows hot-swap. This is very _false_. It has lead to repeat complaints about 3Ware cards, from the _software_ RAID standpoint. That's because from a software RAID standpoint, the 3Ware card offers _nothing_ over a "regular" ATA or SCSI card. ;->
The data would always be there after we rebooted, but a reboot was necessary. A few years ago we migrated
everything
to 3ware hardware RAID, and now we rely on our alert
system,
instead of our users, to tell us when a drive fails.
For any hardware RAID, you must have compatible releases: driver + firmware + user-space
That typically means ensuring you have the same versions for each. That's the only issue I've ever run into.
Some software RAID propoents will say that's a headache. In 6 years of 3Ware RAID deployments, I can say the piece of mind with hardware RAID and its _total_ abstraction, is well worth this little headahce.
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Bryan J. Smith -
David Thompson