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).
Is booting from mirrored vdev created by using ZFS similarly
iffy? That is, if one disk in the vdev dies, will the machine
panic?
Cheers,
--
Rich Teer, SCSA, SCNA, SCSECA
CEO,
My Online Home Inventory
URLs: http://www.rite-group.com/rich
http://www.linkedin.com/in/richteer
http://www.myonlinehomeinventory.com
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
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). > Is booting from mirrored vdev created by using ZFS similarly > iffy? That is, if one disk in the vdev dies, will the machine > panic? > >The machine should not panic and should be bootable, if properly configured. -- richard
Are you using set md:mirrored_root_flag=1 in /etc/system? See the entry for md:mirrored_root_flag on http://docs.sun.com/app/docs/doc/819-2724/chapter2-156?a=view keeping in mind all the cautions... This message posted from opensolaris.org