hot-add unformatted drive to RAID array automagically
We're about to purchase a new server box that has to be as easy to
maintain and as fail-safe as (within reasonable bounds) possible.
Obviously one of the most sensitive and messy failure components are the
hard drives. To defend against random drive failures, I want to have a
machine that will do RAID-1 (simple mirroring) with two active drives
and one hot-standby drive.
That's easy to setup with mdadm, but my goal here is to make this system
as easily maintainable as possible. I'm assuming that a clueful
administrator that will know how to prepare the new disk and then add
it to the array will NOT be around, so this is how it has to work:
When a disk fails, one has to be able to just pull it out of the running
box (hot swap). In the meantime, the array will be rebuilding with the
hot-standby disk, so in a couple of hours there will be a functional
RAID-1 array again, but with no standby disk.
After buying a new (unformatted) disk, the maintainance person will then
just have to plug the new disk in the box, at which point it will be
recognized and added (as a hot standby) to the array.
No partitioning, no typing, no downtime. With what kind of hardware is
this possible? I assume SCSI hot-swappable drives, the right case and a
SCSI RAID controller will do the job. Can anyone recommend specific
controllers that will play nicely with Debian (sarge)?
We have the functionality described above with a M$ box running on a HP
Proliant server with a RAID-5 configuration. If RAID-5 is simpler to
implement than RAID-1 + hot-standby, we'll go for that (although the
latter minimizes the chance of loosing the filesystem).
If I'm mistaken in thinking that mdadm cannot offer the functionality
we're looking for (hot-add unformatted drive with no admin input), I'd
be more than happy to be corrected!
Awaiting your suggestions/experiences
-A
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