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Clearing Equallogic Lost Raid Blocks

When there are issues with a lost block condition on a RAID volume on an Equallogic member, you may receive a "RAIDset lost blocks error" via the Group Manager or via an email/smtp message.

To get more info on the lost block(s), simply ssh in to an IP address of the member with the error and issue the following commands:

su exec 'raidtool'

Look for an error similar to *!! RAID LUN contains 8 lost blocks. !!* in the output:

*!! RAID LUN contains 8 lost blocks. !!*
(raidtool -W 1) clears blocks.
(raidtool -w 1) lists blocks.
14 Drives (14,15,16,46,18,19,20,21,22,23,24,25,26,27)
RAID 50 (64KB sectPerSU)
Capacity 23,489,351,516,160 bytes

In this example, we see that LUN 1 contains 8 bad blocks. To list the the bad blocks, we will use a -w (followed by LUN number) switch in the raidtool utility and to clear the lost blocks, we will use the -W (followed by LUN number).

List bad blocks:

su exec 'raidtool -w 1'

Clear bad blocks:

su exec 'raidtool -W 1'

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  1. Very nice short and to the point article to list and clear the lost blocks. But after listing the lost blocks, how to verify if the lost blocks had data in it or those blocks were empty to begin with? What exactly clear bad blocks do? (i believe it will just write 0s and clear any data if there were some). Is there a better way to make sure i am not clearing data which could be recovered somehow otherwise?

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