> Swap on raid1 IS possible with version 0.90.
What's more interesting for me: how about swap on RAID-5 ?
I currently run a setup with 4 SCSI HDDs with SW-RAID5 and root-fs on md0.
Each of these HDDs currently has a std swap partition and fstab swap entry
with same priority (so kernel automagically distributes swap requests on all
disks). This is a simple and fast setup, but it is not crash-safe: if one
swap hdd gets defective, system may/will crash.
So what's best and definitely working in that case:
RAID-1 4x mirror (doesn't look like making much sense)
RAID-1 two 2x mirrors with same swap priority
RAID-5 swap space on 4 disks (parity calc overhead !?)
I read some comments in the docs (or source?), that swapping on RAID does
NOT work. Are these docs / comments outdated ? If yes: maybe RAID authors
should better remove them and instead put in a note that swapping on
RAID-0/1/5 is possible now !?
> As has been suggested by others I'd also recommend setting your
> partitions to type fd to allow autodetection & automatic startup.
Doing that anyway ;-)
> That's why I'm using wap on raid in my production servers as well; with ide
> disks failure of one of the disks is handled very well, on scsi raid
> systems there have been numeous reports that the scsi layer or driver will
> have problems after a disk failure and you may have to restart the system
> after a disk failure.
I had some "simulated" crashes (done to test RAID) and one real yet (all
SCSI).
In some of the simulated cases and in the real one, too, things worked as
one would expect (being positive ;-).
But in one or two cases, SCSI layer ended up in endless retries / bus
resets trying to get the "defective" disk to work again.
Thomas
