On Thu, Jun 12, 2008 at 07:29:08AM -0700, Rich Teer wrote:
> Hi all,
> 
> Booting from a two-way mirrored metadevice created using SVM
> can be a bit risky, especially when one of the drives fail
> (not being able to form a quarum, the kernel will panic).

SVM doesn't panic in that situation.  At boot time, root is mounted
read-only, so a panic is unnecessary to protect the filesystem.

Instead the boot process stalls and you get a shell that lets you
resolve the replica states manually (usually by deleting the replicas
from the dead drive).  

Panic should only happen if you're already running and you then lose
more than 50% of replicas (uncommon in 2 disk setups).

> Is booting from mirrored vdev created by using ZFS similarly
> iffy?  That is, if one disk in the vdev dies, will the machine
> panic?

Good question.  SVM by default stalls the boot to ensure a strict
quorum.  VxVM continues the boot even though only 50% of DB are
available.  I think this is because it uses a timestamp/generation ID to
resolve which copy is more up-to-date.

-- 
Darren
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