On Sun, May 5, 2013 at 4:46 PM, Justin Cormack
<justin@xxxxxxxxxxxxxxxxxxxxx> wrote:
On Sun, May 5, 2013 at 1:00 PM, Alexander Gladysh <agladysh@xxxxxxxxx> wrote:
I mean that we were *not* happy with the level of isolation that
OpenVZ provided (several years ago).
Are there any texts documenting experience with LXC under high load
scenarios? I'm especially interested in rationing HDD between several
VMs (containers?), including a few very aggressive HDD users.
In our experience, this is somewhat problematic even for Xen (but it
is possible that we don't wield it good enough).
Seriously just get SSD. You cannot expect to ration 100iops sanely
between multiple processes and get anything much useful for aggressive
users. Suspect you have marginally more control under lxc as all the
requests are seen by the same kernel. You end up with pretty much the
same tools, or you can customise the elevator. But an SSD is much more
useful.
The point is to avoid degradation of performance for non-aggressive
users if aggressive ones get carried away. (Just in case: by user here
and above I meant a VM.)
If aggressive users do get carried away, they are to be fixed and
optimized. But this is not instantaneous. Meanwhile rest of the system
should work (possibly in a gracefully degraded mode). Otherwise
virtual cluster tends to "blow up" with unpleasant consequences.
