On 17/06/13 09:40, Petros wrote: > Hi Russell, > > From: "Russell Coker" <[email protected]> >> I've got a virtual server running MySQL where I'm going to convert >> the Dom0 to >> ZFS. Currently the Dom0 exports a LVM volume to the DomU which uses Ext4 for >> the database. My options are to use a ZFS zvol instead of a LV for the Ext4 >> filesystem or to use a ZFS filesystem that is NFS exported. > > There may be a third option: Running MySQL in a Linux container. This > way the "Dom0" is sharing the kernel with the "DomU" and provides the > filesystem directly, without any layer in-between. Definitely a plus > for a database server. > > It's the setup I use with FreeBSD and jails and it works well. > > In some cases it is worth to consider whether you need OS > virtualisation at all. E.g. database servers on dedicated hardware > shared by multiple instances. > > I agree with Arjen to stay away from NFS. Partially because of the way > NFS adds networking and locking over it and all that complexity (and > potential implementation problems and bugs..) > > I see issues reported around ZFS and NFS under FreeBSD but I did not > bother to look into it - I don't use it that way (and can afford to > avoid it;-) > > Arjen, I am surprised to hear the ZFS is faster than ext4. I did not > benchmark (the performance is "good enough" for my purposes) but I > believed a COW system isn't the best for databases.
I've noticed ZFS performing very well for databases as well, and wrote a blog post about it: http://blog.dryft.net/2011/09/benchmarking-zfs-xfs-ext4-and-btrfs.html My blog post also notes that I have my suspicions about WHY it's faster -- that perhaps it is not using i/o barriers. I don't know if that has any implications for data write assurances or not in the ZFS COW model; it's quite possible that it's actually safe to not use barriers, and thus gain a big performance boost. Does anyone here know more about this? PS. That round of benchmarking was in 2011, when zfs was not particularly mature on Linux; the situation may have changed by now. _______________________________________________ luv-main mailing list [email protected] http://lists.luv.asn.au/listinfo/luv-main
