Re: LVM Snapshot Troubles

[Michael Vrable <mvrable@cs.ucsd.edu>]

I've been looking into the LVM snapshot/memory allocation troubles and
will try to come up with a fix.

FYI: In doing more searching for information about the problem, I did
come across this:
    http://www.redhat.com/archives/dm-devel/2004-January/msg00068.html

    "The problem seems to be that dm-ioctl-v4.c sets the PF_MEMALLOC
    flag for the current process.

    Lookaing at the memory allocator (__alloc_page) this means that the
    VM will think the memory allocation is already running (and this is
    a recursion) so it will not try to free pages / rebalance page or
    whatever." ...

I'm looking into sharing memory between the snapshots instead of giving
each snapshot its own private allocation of pages for I/O.  (As I'd like
to scale to a large number of snapshots, and don't want to need >1 MB of
kernel memory per snapshot.)

--Michael Vrable


-------------------------------------------------------
This SF.net email is sponsored by: IT Product Guide on ITManagersJournal
Use IT products in your business? Tell us what you think of them. Give us
Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more
http://productguide.itmanagersjournal.com/guidepromo.tmpl