Hello Everyone!!
I have a general linux question about how ram and swap are used in zentyal/ubuntu
First my setup:
Server running latest zentyal 2.2.6 with everything up to date.
Server hardware:
2x xenon E5606 processors (4 cores each)
10 gigs DDR3-1600 ram (5 slots with 2 gig sticks.... non ECC ram)
I have two 500 gig drives which I have setup in software raid1 using MDADM
I created 3 partions. One for the root file system (30 gigs) EXT4, one for home (450 gigs) EXT4 and one I use for swap (20 gigs)
I also have 7 x 2TB seagate 5900RPM drives running in a software raid 6.
One top of my core zentyal installation I also run Virtualbox. Which has two virtual servers running (One is a webserver and the other I am testing and Enterprise Resource Planning System). The webserver has about 3 gigs or RAM allocated to it and the ERP system has about 1.5 gigs RAM allocated to it.
This leaves the main system about 5.5 gigs of RAM.
Now here is my question. I have noticed that my system is using 2.84 gigs of swap and according to what the munin graphs are telling me I have seen a maximum of 524 pages/second of swap out.
I am trying to figure out why my system is using so much swap??? Is this normal???
Last night I changes the stripe_cache_size for my raid6 array from default 256 to 8192. This has improved my write and read speeds to about 120 Mb/s (fully maximizes my gigabit lan). However now I see my load jump during large file transfers and see a lot more swap being used in the beginning of the transfer. As the transfer continues I see load go down.
When I look to see what is causing the high load I always notice a lot of swap activity at the same time. Why am I using swap when I have 5.5 gigs of RAM
?