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>One of the nice things about Xen is that disk I/O can be controlled somewhat because each domU has a specific process in dom0 for disk access. So you can ionic
by lsc 16y ago
>One of the nice things about Xen is that disk I/O can be controlled somewhat because each domU has a specific process in dom0 for disk access. So you can ionice things & provide a somewhat more controlled access to the disk.
My experience? it's easy to make one customers's I/O suck with such tools, but they work for shit when it comes to fairly balancing everyone's I/O.
As far as I can tell, the best practice is to monitor everyone's usage, and if someone goes above some pre-set threshold, to make their I/O suck using ionice or what have you.
But that's a long way from solving the problem.
- tres 16y agoYeah, for certain. I guess I just really, really like the ability to have some control. Even if it isn't solving the problem. Back when I was working for a shop doing OpenVZ, all we could do is shrug our shoulders & make our best guess as to what was causing the problems.
- lsc 16y agoYeah, I know what you are saying. I started on FreeBSD Jails; and god damn, that was /hard/ - the heavy disk users would wipe out everyone else's cache, and so for the light users, when they logged in? the system would behave as if it did not have any pagecache. Moving to Xen, even without doing any I/O limiting, was world changing, simply because heavy users could not overwrite the pagecache used by light users.