Re: Raid5 read error correction log

2006-06-04 Thread Neil Brown
On Saturday June 3, [EMAIL PROTECTED] wrote:
 Hey Neil,
 
 It would sure be nice if the log contained any info about the error
 correction that's been done rather than simply saying read error
 corrected, like which array chunk, device and sector was corrected. I'm
 having a persistent pending sector on a drive, and when I do check or
 repair, it says read error corrected many times, but I don't know
 whether it's doing the same sector over and over or if there are just so
 many of them...  I seem to remember reading something about this on the
 list some time ago, is it already in the kernel? (I'm running 2.6.17-rc4
 now).

Yes added to todo list:
   include sector/dev info in read-error-corrected messages

 
 Btw, when it does correct a read error, I assume it also tries to read
 it again to verify that the correction worked?

Yes.  It doesn't check that the read returns the correct data, but it
does check that a read succeeds.  However I'm not certain that the
read request will punch through any cache on the drive.  It could be
that the reads return data out of the cache without accessing data on
the surface of the disk

NeilBrown
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Re: problems with raid6, mdadm: RUN_ARRAY failed

2006-06-04 Thread Neil Brown
On Friday June 2, [EMAIL PROTECTED] wrote:
 I have some old controler Mylex Acceleraid 170LP with 6 SCSI 36GB disks on
 it. Running hardware raid5 resulted with very poor performance (7Mb/sec in
 sequential writing, with horrid iowait).
 
 So I configured it to export 6 logical disks and tried creating raid6 and see
 if I can get better results. Trying to create an array with a missing 
 component
 results in:
 
 ~/mdadm-2.5/mdadm -C /dev/md3 -l6 -n6 /dev/rd/c0d0p3  /dev/rd/c0d2p3 
 /dev/rd/c0d3p3 /dev/rd/c0d4p3 /dev/rd/c0d5p3 missing
 mdadm: RUN_ARRAY failed: Input/output error

There should have been some messages in the kernel log when this
happened.  Can you report them too?

Thanks,
NeilBrown
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