[linux-lvm] Error setting up a mirrored lv
harik at chaos.ao.net
Tue Jul 18 19:16:13 UTC 2006
Laurenz, Dirk wrote:
> i'm doing this:
>>> hgest3301:~/LVM2.2.02.06 # lvcreate -m1 -n lvmirror -L 10G
>>> vgtest /dev/dm-55 /dev/dm-56
>>> Not enough PVs with free space available for parallel allocation.
>>> Consider --alloc anywhere if desperate.
> what's wrong?
> Is there any documentation out there?
> Why do we need three pvs? for a mirror?
> Are there any other options?
As you noticed, you need a log partition. dm-mirror is a bit smarter
then the basic MD raid1 in that it uses a log disk to keep track of
write completions for synchronization. I've only recently got a kernel
that supports modern mirror, but it looks like the log file sticks at a
single extent even with a 20gb mirror (all my free space).
Is there a reason that the mirror is on a separate volume rather then a
serialized metadata chunk at the end of each? Just for seektime
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