tmp wrote:
I read the software RAID-HOWTO, but the below 6 questions is still unclear. I have asked around on IRC-channels and it seems that I am not the only one being confused. Maybe the HOWTO could be updated to clearify the below items?
1) I have a RAID-1 setup with one spare disk. A disk crashes and the spare disk takes over. Now, when the crashed disk is replaced with a new one, what is then happening with the role of the spare disk?
the new disk is spare, the array doesn't revert to it's original state.
Is it
reverting to its old role as spare disk?
so no it doesn't.
If it is NOT reverting to it's old role, then the raidtab file will
suddenly be out-of-sync with reality. Is that correct?
yes raidtab is deprecated - man mdadm
Does the answer given here differ in e.g. RAID-5 setups?
no
no it doesn't. You could use the whole disk (/dev/hdb).
2) The new disk has to be manually partitioned before beeing used in the array.
In general, AFAIK, partitions are better as they allow automatic assembly at boot.
nothing special - eventually, if you replace all the partitions with bigger ones you can 'grow' the arrayWhat happens if the new partitions are larger than other partitions used in the array?
What happens if they are smaller?
it won't work (doh!)
3) Must all partition types be 0xFD? What happens if they are not?
no They won't be autodetected by the _kernel_
4) I guess the partitions itself doesn't have to be formated as the
filesystem is on the RAID-level. Is that correct?
compulsory!
5) Removing a disk requires that I do a "mdadm -r" on all the partitions
that is involved in a RAID array. I attempt to by a hot-swap capable
controler, so what happens if I just pull out the disk without this
manual removal command?
as far as md is concerned the disk disappeared. I _think_ this is just like mdadm -r.
Aren't there some more hotswap-friendly setup?
What's unfriendly?
6) I know that the kernel does stripping automatically if more partitions are given as swap partitions in /etc/fstab. But can it also handle if one disk crashes?
no - striping <> mirroring The kernel will fail to read data on the crashed disk - game over.
I.e. do I have to let my swap disk be a
RAID-setup too if I wan't it to continue upon disk crash?
yes - a mirror, not a stripe.
David
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