Data that can't be store on the foulty device should be keep in the bitmap. Next when we reatach missing third drive when we write missing data from bitmap to disk everything should be good, yes? I'm thinking correctly?Bitmap doesn't record writes. Please read: https://man7.org/linux/man-pages/man4/md.4.html bitmap is used to optimize resync and recovery in case of re-add (but we know that it won't work in your case).
Is there a way to make storage more fault tolerant?
From what I saw till now one array=one PV(LVM)=LV(LVM)=one FS.
Mixing two array in LVM and FS isn't good practice.
But what about raid configuration?
I have 4 external backplane, 12 disk each. Each backplane is
attached by external four SAS LUNs.
In scenario where I attache three disk to one LUN and one LUN
crash or hang and next restart or ... data on the array will be
damaged, yes?
I think that I can create raid5 array for three disk in one LUN
so when LUN freeze, disconect, hungs or etc one array will stop
like server crash without power and this should be recovable(until
now I didn't have problem with array rebuild in this kind of
situation)
Problem is with disk usage, each 12 pcs backplane will use 4 disk
for parity( 12 disk=4 luns = 4 raid 5 array).
Is there better way to do this?
And I failed to start it, sorry. It is possible but it requires to work withsysfs and ioctls directly so much safer is to recreate an array with --assume-clean, especially that it is fresh array.I recreated the array, LVM detected PV and works fine but XFS above the LVM is missing data from recreate array.Well, it looks like you did it right because LVM is up. Please compare if disks are ordered same way in new array (indexes of the drives in mdadm -D output). Just do be double sure.
How can I assigne raid disk number to each disk?
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