[linux-lvm] Re: Proper method of snapshotting XFS with external log using LVM2

Milan Broz mbroz at redhat.com
Wed Aug 1 17:24:47 UTC 2007

Mario Becroft wrote:
> 2. I tried without xfs_freeze anyway just to see what would happen, and
> actually in kernel if you simply create a snapshot of the main
> filesystem volume and destroy it several times in a row (not even
> touching the log volume yet) lvcreate hangs.

Well, probably two problems combined here. 

In 2.6.22 is change in block layer which serializes generic_make_request()
calls and it causes some problems with synchronous metadata snapshot updates.
See patch which moves metadata updates to separate thread

Maybe lvcreate hang is just another demonstration of this problem.

Please could you test it with 2.6.21 kernel, or with kernel with this patch applied ?

Is the bug with separate filesystem log reported in bugzilla ?

If you find problem with even patch above, please report it with
exact description how you reach this.

mbroz at redhat.com

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