[linux-lvm] Solving the "metadata too large for circular buffer" condition
ag2827189 at tagmall.com
Wed Nov 24 20:28:11 UTC 2010
We've just hit this error, and it is blocking any expansion of existing
or creation of new volumes.
which appears to describe a solution. I'm doing some reading, and I've
set up a test environment to try things out (before doing anything risky
to production). But I'm hoping a post here can save some time (and
First: The referenced thread is two years old. I don't suppose there's a
better way to solve this problem today?
I'm not sure how metadata is stored. It seems like, by default, it is
duplicated on each PV. I'm guessing this because one can't just add new
PVs (with larger metadatasize values), but one must also remove the old
metadata. Is that right?
Are there are consequences to removing the metadata from most of the
physical volumes? I've six, so I'd be adding a seventh and eighth (two
for redundancy, though the PVs are all built on RAID sets).
The "pvcreate --restorefile ... --uuid ... --metadatacopies 0" command
would be executed on the existing 6 physical volumes? No data would be
lost? I want to be *very* sure of this (so I'm not trashing an existing
What is the default metadatasize? Judging from lvm.conf, it may be 255.
255 Megabytes? Is there some way to guestimate how much space I should
expect to be using? I thought perhaps pvdata would help, but this is
apparently LVMv1 only.
[Unfortunately, 'lvm dumpconfig' isn't listing any data in the metadata
There's also mention in the cited thread of reducing fragmentation using
pvmove. How would that work? From what I can see, pvmove will move
segments. But even if two segments are moved from dislocated locations
to immediately adjacent locations, I see nothing which says that these
two segments would be combined into a single segment. So I'm not clear
how fragmentation can be reduced.
Finally, there was mention of changing lvm.conf - presumably,
metadata.dirs - to help make more space. Once lvm.conf is changed, how
is that change made live? Is a complete reboot required, or is there a
Thanks for any and all help...
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