Hura, hura, hura! ;-) Well, wonder why it didn't work for me ;-(
Looks good so far, but is you data safe?
I think so.
fsck has found some errors and corrected them.
resync done
cat /sys/block/md4/md/mismatch_cnt
0
Looks good.
This is correct assuming the default layout.
If you asked for "--layout=n3" you would get a 3-way mirror over a1,b1,c1 and
d1,e1,f1 and those would be raid0-ed.
And the question which one is the most efficient is beyond the scope of
our subject I'm of course? Or maybe there is some general rule of thumb
for this?
The more disks the faster array should be *but* the more data to mirror
at once when writing...
Anyway my tests proved that RAID1 on two disks is *much* slower than
RAID10 on 4 disks. RAID10 SATA can easily compete with HP SmartAray
P410i/BBC SAS RAIDs (but in RAID1 only ;-)). Well, at least during
iozone benchmarks.
If you had 5 devices then you get data copied on
sda1+sdb1
sdc1+sdd1
sde1+sda1
sdb1+sdc1
sdde+sde1
so is *any* pair of adjacent devices fail, you lose data.
So from safety point of view there is need for more spare disks or go
for RAID6.
Hard to tell without seeing kernel logs. Almost certainly a hardware issue
of some sort. Maybe a loose or bumped cable. Maybe a power supply spike.
Maybe a stray cosmic ray....
http://pastebin.com/iapZWm0S
Those 'failed' disks are connected to motherboard SATA ports. I've got
also Adaptec 1430 adapter with 2 free ports, maybe I should move those
disks there.
Thank you for all the help and time put into answering my questions.
Piotr
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