Hi,
This email is an attempt to get some knowledge on how softraid works.
There's basically zero docs on these topics out here (all docs are about
how to set it up first & subsequent times in non-failure cases).
If you would be able to respond in "HOWTO form" would be awesome, then
at least this will be the Ultimate Softraid Reference :D
Q1:
Can softraid do
a) Scrub (as in read all the underlying media and check they're in
check, e.g. "raid fsck"),
b) Hotspare (as in have one or more pre-designated physical disks that
the softraid would switch into use if one of the physical disks in use
already breaks),
c) Hotswap (as in I could unplug one of the physical disks in a raid
live, and presuming my HBA allows it, the OpenBSD kernel + softraid will
be happy to plug in and plug out disks live - and I guess perhaps that
needs to play together with the rebuild then)?
Q2:
And, how do you use the rebuild + these three things? Specifically:
a) How do I check the status of a rebuild from the console? (E.g. disk
blablaX rebuilding 12.3% done, get report if the rebuild failed, etc.)
b) How do I plug in a physical disk live into my RAID1 softraid?
c) How do I plug out a physical disk live from my RAID1 softraid?
d) How do I initiate a rebuild on a RAID1 softraid, such as plugging in
the brand new disk sdX into my RAID1 softraid or sdX was used previously
or suffered a power outage or whatever - how do I rebuild it?
e) How do I get a listing of all my softraids and of all the physical
disks plugged into them, from the console?
f) How do I tell softraid to "scrub" i.e. intregrity-check all the
physical disks running in the softraid, including every sector so
actually all of their surfaces are read (presuming that the RAID takes
up all the disks)?
g) How do I tell my RAID1 softraid that if sdX dies, then sdY should be
plugged in (i.e. hot spare)?
Also, how do I get a printout of that configuration from the
console, and how do I remove a hotspare?
h) After I plug out a physical disk from my softraid ( c) above), what
should I generally need to do before unplugging it also physically -
just wait 60 seconds or do some magic "SATA power off" command or the
like? (Given an ultra nice SATA or HW RAID controller such as LSI HBA or
LSI Megaraid.)
i) When I plug in a physical disk on my SAS/SATA HBA (be it an LSI HBA
or LSI HW RAID), will OpenBSD autodetect it and assign a device name for
it just like it does for USB devices so it's complete hotswap/plug and
play?
j) When I plug in a softraid that worked before, what kind of trouble
could happen - if it won't get going at all, should I just reset from
backup, or is there some kind of "rescue rebuild" I could attempt?
k) Do I need to know anything about DUID vs. device name use within the
softraid?
Looking forward to your explanation, thanks!! :DD
Tinker
