G'day all,
I'm using a 2.6.10-rc1 (ish.. some BK just after that) kernel and I have a 10 drive raid-5 /dev/md0.
I noticed SMART telling me I have some pending reallocations on /dev/sdj, so I decided to force the matter with a
mdadm --fail /dev/md0 /dev/sdj1
mdadm --remove /dev/md0 /dev/sdj1
mdadm --add /dev/md0 /dev/sdj1
Fine.. all going well, but I noticed using iostat that instead of doing read-compare cycles, the kernel is rebuilding the drive regardless.
I thought (and I may be wrong) that adding a drive to a raid-5 triggered the kernel to read each stripe, and only write out new parity info if the stripe contents are wrong.
Given this array was idle, and I failed/removed/added the drive within about 10 seconds, I would have thought that about 99.999% of the stripes should be consistent. The kernel however is writing the whole lot out again. (Not a bad thing in this case as it will *force* the block reallocations)
What is going on?
On another note, looks like one of my Maxtors is going south (18 reallocations and counting in the past week). Go on, say I told you so! I have another 15 of them sitting here in a box waiting for the howswap racks to arrive. I guess I'll be testing out Maxtors RMA process soon.
iostat 5
avg-cpu: %user %nice %sys %iowait %idle
31.45 0.00 68.55 0.00 0.00Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn hda 33.87 29.03 1970.97 72 4888 sda 122.58 27187.10 0.00 67424 0 sdb 122.18 27187.10 0.00 67424 0 sdc 122.18 27187.10 0.00 67424 0 sdd 122.18 27187.10 0.00 67424 0 sde 122.58 27187.10 0.00 67424 0 sdf 123.39 27187.10 0.00 67424 0 sdg 123.79 27187.10 0.00 67424 0 sdh 124.60 27187.10 0.00 67424 0 sdi 122.58 27187.10 0.00 67424 0 sdj 141.53 0.00 27354.84 0 67840 sdk 25.00 416.13 335.48 1032 832 sdl 25.40 354.84 380.65 880 944 sdm 26.61 377.42 419.35 936 1040 md0 0.00 0.00 0.00 0 0 md2 79.44 829.03 600.00 2056 1488
Personalities : [raid0] [raid5] [raid6] md2 : active raid5 sdl[0] sdm[2] sdk[1] 488396800 blocks level 5, 128k chunk, algorithm 2 [3/3] [UUU]
md0 : active raid5 sdj1[10] sda1[0] sdi1[8] sdh1[7] sdg1[6] sdf1[5] sde1[4] sdd1[3] sdc1[2] sdb1[1]
2206003968 blocks level 5, 128k chunk, algorithm 0 [10/9] [UUUUUUUUU_]
[>....................] recovery = 0.8% (2182696/245111552) finish=585.3min speed=6913K/sec
unused devices: <none>Oh, while I'm here. If you celebrate Christmas, Merry Christmas! (I have become somewhat more sensitive to this living in an Arab country!)
--
Brad
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