Hi to all, I have a short question regarding which filesystem I should use in Dom0/DomU. I've built my Dom0 on basis of ZFS. For my first DomU I've created a ZFS pool and installed the DomU (with OSOL inside). During the installation process you are being asked if you wanna use UFS or ZFS - I've chosen ZFS. The installation process was incredible slow. Hence, in the next DomU I used UFS instead of ZFS. And the installation process was pretty fast. This leads me to the coonclusion: ZFS on top of ZFS = don't; UFS on top of ZFS = ok Can anybody verify that performance issue? Regards André -- This message posted from opensolaris.org _______________________________________________ xen-discuss mailing list xen-discuss@opensolaris.org
Andre, I am not an expert, I only started using this a few weeks ago, but I think I can help a little.. What type of virtual disk were you using? For sure "flat file" on zfs is *very* slow. I use ZFS on all my (Open)Solaris domU''s. I had problems with "sparse" file based disk images, so I switched. My "disks" are actually zvol''s, shared over iscsi from a Unified Storage 7410c, but I also have a few "local" zvols. These perform well. I assume you followed the examples and advice at http://hub.opensolaris.org/bin/view/Community+Group+xen/virtinstall ? Tommy On Dec 2, 2009, at 8:17 AM, Andre Boegelsack wrote:> Hi to all, > > I have a short question regarding which filesystem I should use in Dom0/DomU. I''ve built my Dom0 on basis of ZFS. > > For my first DomU I''ve created a ZFS pool and installed the DomU (with OSOL inside). During the installation process you are being asked if you wanna use UFS or ZFS - I''ve chosen ZFS. The installation process was incredible slow. > > Hence, in the next DomU I used UFS instead of ZFS. And the installation process was pretty fast. > > This leads me to the coonclusion: ZFS on top of ZFS = don''t; UFS on top of ZFS = ok > > Can anybody verify that performance issue? > > Regards > André > -- > This message posted from opensolaris.org > _______________________________________________ > xen-discuss mailing list > xen-discuss@opensolaris.org
Hi Tommy, thanks for your post. I set the system up as follows: Root ZFS pool "rpool" for osol root installation (RAID 1 hardware mirror) ZFS pool "zpool" for my DomU's (c7t2d0, c7t3d0 -> local SAS disks) On basis of zpool I created a zvol with 50gb and installed the DomU on basis of this zvol. I did this two times: first with ZFS and second with UFS. First installation was pretty slow, second was quite fast. Here is another mail from the mailing list: "Be sure to have single vdevs in your DomU. Any old filesystem would normally fit this description. ZFS is special: it does it's own striping/mirroring, and makes the usual assumptions about your leaf vdevs in order to optimize performance. My recommendation follow from my 'common sense' feeling [2] that ZFS dynamic striping (default operation, but also key in raidz/raidz2/raidz3) will make assumptions about your underlying devices, that just won't hold for virtual disks, especially on LVM/RAID sets or ZFS (ZFS being similar to LVM/RAID in this department)." So "doubling" the effect of ZFS (in Dum0 and DomU) leads to a misbehaviour in regards of performance instead of boosting the performance?! Is this correct? Regards André -- This message posted from opensolaris.org _______________________________________________ xen-discuss mailing list xen-discuss@opensolaris.org