On 9/14/2011 10:04 AM, Felix Miata wrote:
On 2011/09/14 12:15 (GMT+0200) Per Jessen composed:
Felix Miata wrote:
I don't see much point in using RAID for a swap partition either.
If you lose swap on a running system, the system stops running. All my systems have swap-space on RAID1.
Isn't that true only for low memory systems actually using swap? My 24/7 RAID1 system boots with swap enabled, but usually one of the first things I do after boot is swapoff -a. Dedicated swap on systems with ample RAM seems to me to be an anachronism.
On my production servers I haven't even allowed the installer to create a swap partition or swap file since the first server with 4G of ram. It's been years and years and no problems. If oom-killer ever kills anything, it's never been anything we noticed. Of course they don't hibernate or suspend so it's not needed for that either. swap never gets turned on in the first place because there is no swap in /etc/fstab so no need to turn it off. It's been too many machines with too many users doing too much work for too many years to be a debatable topic for me any more. Maybe it's only because of our particular workload and/or other factors that are specific to us, but, even if not necessarily for anyone else, it is definitely a proven theory and an answered question by now at least for us. Basically I just watched my swap usage in top, and determined that the only time any swap was getting used at all was just artificial things that don't count, like things that specifically tested for space by trying to use it. Exapmle: up 127 days, 104 users, Mem Used/Total 3.4G/3.6G , Swap Used/Total 3.1M/8.4G I have swap enabled on that box because of the number of users and the merely 4G ram and the somewhat spike-able nature of the workload it seemed prudent, but clearly it's not actually needed. Heck even on a box with only 2G ram, 47 users, up 44 days, 2G swap, 220K used. _K_. I don't even need it on that little 2G box. I entirely agree about the anachronism as long as your motherboard can support whatever amount of ram you would have used as swap anyways. That 2G box is a crappy little desktop board crammed into a cheap rackmount case. (I didn't buy it or make it or initially install it, but as long as it continues to do it's job I'll continue to let it.) Being a cheap desktop board, it only has two ram slots and can only support 2G ram max. So in that case it seemed like some swap was a good idea to make up for physical motherboard limitations. But that's a completely unusual situation any more and even there it turns out to never get used. -- bkw -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org