[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-users] Xen domU filesystem best-practices question

On Wed, 25 Jul 2007, Nico Kadel-Garcia wrote:

Jeff Bachtel wrote:
 For file-backed disk images used for domUs, what is the current
 best-practice filesystem to use? That is, the filesystem with the
 fewest edge cases and failure modes.

 I was told (6 months back or so), to absolutely not use a journalled
 filesystem on a file-backed image, and so I started moving to ext2. Is
 this advice still pertinent, or would a journalled filesystem now be
 better (XFS or ext3, for instance).



I've been using ext3 with little trouble. Ext3 has the advantage of coping, successfully, with 50,000 files in one directory without hiccup-ing, which ext2 always had trouble with.

I would assume the original suggestion was due to the journalling filesystem's requirement that the journal is written before the raw data. With a file-backed image I can imagine that the write ordering is at the discretion/mercy of the dom0 filesystem layer... whereas with a virtual block device it should be "as requested" by the domU. Could you give your domU's a small block device to use for the journal(s)?

That said, I would expect the modern ext2 logic can handle all the ext3 options like dir_index (which should help with big directories) as long as they aren't journal related.

All the above said, I'm not a developer, just an old sys-admin who likes to pretend he understands how things work :)


Xen-users mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.