[Xen-users] Advice on distributed filesystems, nfs, gfs and so on

[Jose de Paula Eufrasio Junior <jose.junior@xxxxxxxxx>]

So I spent the last 3 to 4 hours trying to figure out how to optimize
sharing content between VMs and Xen Hosts;

I have a fairly simple design, that I am linking here:
http://img297.imageshack.us/img297/4773/path2924.png

Basically, I have a number of VM's that run the same web app, and
there's a load balancer in front of them. There is also an 'adm' vm
that hold the same app, but is accessed directly only by people that
can login and change stuff (add content, configure, etc...) the
application.

There's some content that is added by the admin machine that the
others must see to serve it online, like images or other stuff that
doesn't go into the apps DB. For that I am using a NFS on the Xen
Host. This NFS is mounted RW by the adm VM and RO by the app vms. It
works, but NFS is giving me headaches these last days. The adm VM
sometimes locks the NFS (normally during uploads, sometimes it's not
even a large one). With the NFS locked up all the other VMs starve and
freeze. I changed rsize, wsize and did other configs on the NFS to fix
that. Other example is Lucene index generation, that doesn't quite
agree with NFS sometimes.

What I am llooking for is information on more robust file systems to
acomplish the same. NFS will not cut it when I have to, for example,
migrate VMs from one Xen host to anothe.

I checked on GFS2, and seems that I can use my SAN to share FS between
xen hosts (so putting the images on GFS can make migration easier on
the VM side).. I dont think I can use the app vms as nodes for the GFS
because they VMs are pretty much barebones running only the app and
serving content that is, at the moment, on NFS.

Any idea is welcome.

Thanks.

PS: Sorry if something is written wrong, I am without glasses at the miment! :P

-- 
José de Paula Eufrásio Júnior (coredump)
MCSO, GRC Professional
http://core.eti.br

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