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I'm running linux on a Compaq ProLiant DL360 G2 with two 72 Gb hard disks in RAID-1 configuration. When I shut down the system, after linux is completely halted, both hard disks show intense activity indefinitely (for more than 24 hours). I have to switch off and on the server if I want to start it up again. The server and the hard disks seem to work fine.

Why do the hard drives show this behaviour? Is there any failure in my disks? How can I diagnose it?

Thank you very much in advance for your help.

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I'm ok if the server doesn't power down by itself. My great concern is about hard disk and data integrity, if I power down while the drives are working. –  jpromvi Jun 9 '09 at 15:20

3 Answers 3

up vote 1 down vote accepted

Both of you are right. I have contacted Service Support and I have been told that this behaviour is normal. When the Smart Array Controller is idle for 60 seconds it starts doing surface scans of the disks looking for defective media.

What happens is that linux doesn't power off the RAID. The array becomes idle after shut down and performs this scan indefinitely. There is a gap of about 20 seconds between system halt and the beginning of this process. I guess I can switch off the computer safely at that moment.

Thank you very much for your answers.

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If this a full hardware RAID? If so, it might be a raid scrub going on in the background. I'd check the RAID BIOS and see if it has background scrubbing turned on - it may be continually performing the scrub, but at a lower priority when the system is actively accessing the array.

When the OS is halted but the adapter still has power, the number of I/O ops from the host drops to zero, which allows the raid to give more priority to the scrub.

If this is the case, I'd expect to find an option to disable the background scrub in the BIOS, but that may turn it off all the time, not just when the OS is halted.

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It would be normal to show activity for a while after a server was shut down, due to decaching of data.

If your array does it indefinitely, it may be trying to auto-arrange data or defragment the array. The documentation probably mentions something like that, and if not, you may want to contact server support for more answers.

[EDIT]

You've halted the OS. Is there something unusual with having to power off and on the machine? (If the answer is 'the server should power down by itself', then have you turned acpi=off on the kernelline? If that doesn't work, try 'shutdown -hP now')

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