I believe you're looking for shared writable mmap support, which requires
a very recent (maybe) or painfully-patched FUSE; it's not really up to
GlusterFS (I think it will probably just work, if your FUSE is somehow
able to support it).
I tried to patch my FUSE and gave up (the patches I found didn't work and
caused crashes). I was looking because apt-get uses shared writable
mmap. I found that someone had posted a workaround whereby you'd place
the files requiring shared writable mmap in a tmpfs filesystem; I tried
that, and it worked fine. For apt-get, it wasn't a big deal, as the
mmapped files are just caches; I don't know if the rpm files are something
that would need to be permanent, in which case you'd need to copy the
files in and out of the tmpfs to keep them across reboots.
So, if you can't get shared writable mmap to work, try the workaround
with tmpfs or another filesystem (perhaps even an NFS mount of a GlusterFS
directory).
Thanks,
Brent Nelson
Director of Computing
UF Physics
On Mon, 12 Jan 2009, Gordan Bobic wrote:
Hi,
I'm working on a root-on-glusterfs system and I have almost all of it working
now, but one things that seems to be having problems is RPM (Berkeley DB).
When I attempt to access/query the database that is on glusterfs, I get the
following error:
rpmdb: mmap: No such device
error: db4 error(19) from dbenv->open: No such device
error: cannot open Packages index using db3 - No such device (19)
error: cannot open Packages database in /var/lib/rpm
From the error, it looks like it is having a problem with mmap (or lack
thereof). Presumably, it wants writable mmap.
So:
1) Is there writable mmap support anywhere on the horizon for GlusterFS?
2) Does anyone know if there is a way to make the RPM DB work without mmap?
The only other workaround I can think of that could be applied (I am only
interested in AFR/mirroring) would be to set up DRBD+GFS just for replicating
the RPM DB, but that's a bit lame, because the main reason for using
GlusterFS for a shared-root environment is specifically to avoid having to
use a block level mirroring solution like DRBD+GFS.
Has anyone got any ideas on this?
Thanks.
Gordan
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