On Mon, 15 Oct 2012, Daniel Pittman <[email protected]> wrote: > > For the mail spool a zvol would be a bad idea, fsck on a 400G Ext3/4 > > filesystem is a bad thing and having the double filesystem overhead of > > Ext3/4 on top of a zvol is going to suck for the most disk intensive > > filesystem. > > zvol is more like an LVM logical volume than a filesystem, so the > overhead isn't nearly as much as this comment suggests. That said, > running ext3 (especially) or ext4 on top of it is going to be slower, > and means you can't use the RAID style features of ZFS, and you give > up object level checksums.
I had the impression that a zvol gets all the consistency benefits of ZFS but for a block device. ZFS on top of a zvol may not be a good idea as ZFS is fairly heavy, BTRFS on top of a zvol might be an option though. > > Any suggestions? > > I would aim to run ZFS in the mail domU, and treat the zvol as a > "logical volume" block device. You will have some overhead from the > double checksums, but robust performance. It treats the underlying > dom0 ZFS as a fancy LVM, essentially. You probably also need to > allocate substantially more memory to the domU than you would > otherwise. Yes, lots more RAM in both Dom0 and DomU. The problem is that I have servers with 16G of RAM that I'd prefer not to upgrade. > My fallback would be NFS shared ZFS in the domU - much cheaper because > you only have one ARC, set of checksums, etc, to manage, but with the > added bonus of NFS between the domU and dom0. Fun times. > > Are you sure that LXC or OpenVZ wouldn't better fit your needs than > Xen? You trade off marginally less isolation between containers for > the simplicity of having a single kernel image - so native ZFS > performance. That's a possibility. What is the support for them like in Debian/Wheezy? On Mon, 15 Oct 2012, Jason White <[email protected]> wrote: > XFS doesn't have the fsck problem, but it isn't optimized for large numbers > of small files, as I recall. I can't comment on reliability/performance. I > don't know much about JFS either - XFS seems to be receiving more > development attention from Red Hat and elsewhere at the moment. I don't > think Reiser 3 is seeing much work anymore either. XFS has had FSCK problems in the past. I think that JFS is as good as dead. Even before Hans was arrested there were some issues with ReiserFS such as the fact that hostile data written to a file by a user could cause a corruption at FSCK time. If you use ReiserFS for any server that allows binary data to be stored by a user then you risk security problems. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/ _______________________________________________ luv-main mailing list [email protected] http://lists.luv.asn.au/listinfo/luv-main
