On 01/03/13 21:12, Brian Candler wrote: > On Fri, Mar 01, 2013 at 03:30:07PM +0600, Nikita A Kardashin wrote: >> If I try to execute above command inside virtual machine (KVM), first >> time all going right - about 900MB/s (cache effect, I think), but if I >> run this test again on existing file - task (dd) hungs up and can be >> stopped only by Ctrl+C. >> Overall virtual system latency is poor too. For example, apt-get >> upgrade upgrading system very, very slow, freezing on "Unpacking >> replacement" and other io-related steps. >> Does glusterfs have any tuning options, that can help me? > > If you are finding that processes hang or freeze indefinitely, this is not > a question of "tuning", this is simply "broken". > > Anyway, you're asking the wrong person - I'm currently in the process of > stripping out glusterfs, although I remain interested in the project. > > I did find that KVM performed very poorly, but KVM was not my main > application and that's not why I'm abandoning it. I'm stripping out > glusterfs primarily because it's not supportable in my environment, because > there is no documentation on how to analyse and recover from failure > scenarios which can and do happen. This point in more detail: > http://www.gluster.org/pipermail/gluster-users/2013-January/035118.html > > The other downside of gluster was its lack of flexibility, in particular the > fact that there is no usage scaling factor on bricks, so that even with a > simple distributed setup all your bricks have to be the same size. Also, > the object store feature which I wanted to use, has clearly had hardly any > testing (even the RPM packages don't install properly). > > I *really* wanted to deploy gluster, because in principle I like the idea of > a virtual distribution/replication system which sits on top of existing > local filesystems. But for storage, I need something where operational > supportability is at the top of the pile. I have to agree; GlusterFS has been in use here in production for a while, and while it mostly works, it's been fragile and documentation has been disappointing. Despite 3.3 being in beta for a year, it still seems to have been poorly tested. For eg, I can't believe almost no-one else noticed that the log files were busted.. nor that the bug report has been around for quarter of a year without being responded to or fixed. I have to ask -- what are you moving to now, Brian? -Toby
