When a system boots from a mirrored meta device, does it always sync from
the lowest submirror (e.g., Submirror 0) to the highest submirror (e.g.,
Submirror 1)? Is there a way to force a resynchronization from the highest
Submirror to the lowest Submirror (this would be helpful when you trash
the primary mirror when booted from CDROM, and don't want to corrupt the
working mirror when you reboot). I usually control this my moving RC
scripts and booting from the secondary mirror, but wanted to see what other
methods existed. The section "RAID-1 Volume (Mirror) Resynchronization" on
docs.sun.com doesn't seem to address this specific scenario:
http://docs.sun.com/app/docs/doc/816-4520/6manpiejc?a=view
Thanks,
- Ryan
On Tue, 19 Jul 2005, UNIX admin wrote:
Our Solaris boxes were installed by vendor. I
observed that:
1. Dump device: /dev/dsk/c1t0d0s1 (dedicated)
2. /dev/dsk/c1t0d0s1 is part of mirror
/dev/md/dsk/d1
3. /dev/md/dsk/d1 is the swap
See the following script for details.
Questions:
1. I wonder why the vendor uses /dev/dsk/c1t0d0s1 as
dump device? Is it because writing to another disk
slice is a waste of
time during the emergence of system crash?
This was a configuration oversight on part of the vendor. Sun documentation
clearly states that the dump device should be the mirrored swap metadevice.
It's also a most common blunder sys admins make when setting up mirroring on
their own, since it's easy to forget.
2. Will Solaris accept writing data into only one
part of mirror like this? if yes, will Solaris copy
the data from this part to another part of the
mirror?
Yes, but the data won't be mirrored because [I]metadevices are mirrored, not
physical devices[/I].
3. Should I use "dumpadm -d swap" to make Dump device
as /dev/md/dsk/d1?
Absolutely! And also ensure that the swap metadevices ARE NOT synced at
reboot (there is no need):
metaparam -p 0 /dev/md/dsk/<swap metadevice>, for example:
If d10 is a swap metadevice with submirrors d11 and d12,
metaparam -p 0 /dev/md/dsk/d10
So in your case:
dumpadm -d /dev/md/dsk/d1
metaparam -p 0 /dev/md/dsk/d1
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