Jeff Bachtel
2007-Jul-25 15:27 UTC
[Xen-users] Xen domU filesystem best-practices question
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). Thanks, Jeff _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Nico Kadel-Garcia
2007-Jul-25 16:25 UTC
Re: [Xen-users] Xen domU filesystem best-practices question
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). > > Thanks, > > Jeff >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. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Tom Brown
2007-Jul-25 18:37 UTC
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). >> >> Thanks, >> >> Jeff >> > 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 :) -Tom _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users