Having the problem ‘solved’ is probably subjective based on what your I/O expectations/requirements are. Adding at least one write-optimized SLOG should improve the situation significantly. Adding another SLOG should improve things further (more fast I/O capacity available for sync writes) but perhaps not to the same degree. Here we use Intel 3700 SSDs (the 200G version), which also have power protection, and they seem to work rather well.
The virtio drivers will obviously continue to cause some overhead to I/O and you shouldn’t expect performance inside a KVM to equal a native OS zone. FYI, I also did some experimentation across multiple versions of the virtio drivers in Windows and found a up to a 70MB/sec difference in write speeds so that might be something else to look into. On 19 Jan 2015, at 9:04 am, Greg Zartman via smartos-discuss <[email protected]<mailto:[email protected]>> wrote: On Sun, Jan 18, 2015 at 10:40 AM, Ian Collins <[email protected]<mailto:[email protected]>> wrote: Greg Zartman via smartos-discuss wrote: Yes, that is exactly the issue I'm seeing and this link does explain it much better. I thought I'd seen this discussion at some point, but forgot about it. You had quite a long discussion with me about it.... That's right, we did talk about it when I first started using SmartOS and was playing with different raid configurations and what not and mainly learning. Since this time; I've mainly deployed Smartmachines, so I'd not seen any issues with the virto drivers and the synchronous write issues being discussed here. The Centos VM I'm working with now is the first time I've tried to deploy a kvm vm container like this in a high traffic production environment. Unfortunately, the disk speeds I'm getting now just aren't usable. If the management GUI is timing out, then the VM is pretty much useless. I can get better performance and no GUI time outs with an atom processor and 1G of RAM -- basically a couple hundred bucks in used hardware. I'm just trying to understand this and figure out what I need to do to get a useable performance out of SmartOS KVM. Are you saying that a SLOG device is going to solve the problem? Should I install 2 SLOG devices and strip them? Thanks, Greg smartos-discuss | Archives<https://www.listbox.com/member/archive/184463/=now> [https://www.listbox.com/images/feed-icon-10x10.jpg10f3ec5.jpg?uri=aHR0cHM6Ly93d3cubGlzdGJveC5jb20vaW1hZ2VzL2ZlZWQtaWNvbi0xMHgxMC5qcGc] <https://www.listbox.com/member/archive/rss/184463/25738179-216c4b5f> | Modify<https://www.listbox.com/member/?&;> Your Subscription [https://www.listbox.com/images/listbox-logo-small.png10f3ec5.png?uri=aHR0cHM6Ly93d3cubGlzdGJveC5jb20vaW1hZ2VzL2xpc3Rib3gtbG9nby1zbWFsbC5wbmc] <http://www.listbox.com/> ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
