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Problem with AutoRAID disk replacement

Vincent Farrugia
Honored Contributor

Problem with AutoRAID disk replacement

All 12 18Gb disks in the array, Disk B2 was constantly on amber the whole time. Controllers green or flashing green. Array State READY. Auto Rebuild on, Auto Include on, Active Hot Spare on. arraydsp -a did not reveal anything awry... everything was good and every disk was included. Disk B2 was not
even included in the list. From control panel, number of disks included were 11, not 12. Did not require rebuild (since it has a hot spare, I thought the array was rebuilding the disks to it).

I removed the disk and inserted a new A3714-60001 disk. Disk LED was first amber, then it switched off. For some reason, although we never used the disk, the system reported that the disk was used in another array, so it
couldn't be auto included. I manually included the disk, and the array state returned to ready and green state. For some reason, it did not require a rebuild! I thought that the disk will be rebuilt from the hot spare, but it didn't. I started a manual rebuild to no avail. Number of disks reported by arraydsp -a, control panel and sam was 12 now, not 11. For some reason,
though, the disk was never accessed by the autoRAID. It never had a read or write request on the disk. Array status is READY, for the autoRAID everything is fine. The customer did not report any data corruption. But it's strange that disk B2 never ever rebuilded and never ever flashed its LED for read or write.

The AutoRAID contains 4 LUNS of 18Gb each, so there is relatively small amount of data. Firmware on both controllers is HP60. What could be the issue? Customer is working fine, but there is still this issue.

Many thanks,
Vince
Tape Drives RULE!!!
6 REPLIES
A. Clay Stephenson
Acclaimed Contributor

Re: Problem with AutoRAID disk replacement

I've seen this behavior before on AutoRAID's with very little used capacity. Not having access to the source code, I am forced to guess. I suspect that the controller software has already determined that the data is sufficiently striped so that the gains from a rebuild would be negligible.

If all 12 disks indicate that they are now included then all is well. If this really bothers you then you can force a rebuild from the front panel. Menu -> Disk Changes -> Start Rebuild. Even in this case, I suspect that the rebuild will complete in only a few seconds.
If it ain't broke, I can fix that.
Vincent Farrugia
Honored Contributor

Re: Problem with AutoRAID disk replacement

Hello,

I tried to force this rebuild myself but the array just told me READY immediately. Attached please find the output of armdsp -a after the drive was replaced.

Thanks for your help so far,
Vince
Tape Drives RULE!!!
Joshua Scott
Honored Contributor

Re: Problem with AutoRAID disk replacement

Vince,

Sometimes the AUTORaid systems aren't very "smart". Adding a new disk doesn't guarantee that it will be used for data immediately. The data remains on the disks it was previously on, but it will be rebalanced over time.

The thing to remember is that the total throughput of the connection to the array is 20MB/s, and each disk is 10MB/s. you would probably gain nothing in the way of performance from the disk being unused. I suggest to wait a few days, and see if the new disk is being accessed then.

There's also a small chance that the green LED is not functioning on that disk unit.

Josh
What are the chances...
A. Clay Stephenson
Acclaimed Contributor

Re: Problem with AutoRAID disk replacement

That is exactly as I expected. All is well. You will find that over the next few days that the new drive is used more and more.
If it ain't broke, I can fix that.
Vincent Farrugia
Honored Contributor

Re: Problem with AutoRAID disk replacement

Hello,

The green LED on the disk is working because when I do armlog on it, it flashes green slightly before giving me the output.

I will monitor the AutoRAID in the next few days to see what will happen. Many thanks so far.

Vince
Tape Drives RULE!!!
Vincent Farrugia
Honored Contributor

Re: Problem with AutoRAID disk replacement

Hello,

Just to let you know what happened.

The drive is STILL not being used by the AutoRAID. According to response centre, this is normal if you have a small amount of data, like the customer has. If there is increasing data, this disk will be used for performance.

Case Closed, thanks for everybody's help.

Vince
Tape Drives RULE!!!