glance memory reporting

[Michael Murphy_2]

Hello,

Glance shows memory on one of my machines at 97% utilization. I had heard in the past that this is not necessarily a bad thing (need to check other things). Can someone refresh the other things to check (sar? glance swap?) and give advice on when to order more memory?

[Sridhar Bhaskarla]

Hi Michael,

While others may not agree with me but I say it is a bad thing if it is a production server doing online transactions. I would start worrying if it reaches 90% as you have to have 10% headroom for any growth. Ideally memory usage shouldn't increase over the time but it is not necessarily true.

If it is not a critical server, yes it is not a bad thing to see it 97%. You will need to keep an eye on the pageouts. You can use either glance or 'vmstat' to find them out. Since you have glance, in the same memory window keep looking at "Page out" line. If it is constantly a number, then you are paging out. You don't want to have anything under Deactivations as it will substantially decrease the performance.

Do a 'swapinto -tam' and look at "MB Used" column corresponding to 'dev' lines. If you see some number there, then then there is pageouts happening.

-Sri

[Elena Leontieva]

Hi,

Run these commands:

vmstat -S 5 5 (disregard the first line) and look for si and so

sar -w 5 5

Also, if your system does swapping, check your buffer cache size in glance, may be it is set too large ( more than 400 MB).

Elena.