Remember that under linux, all of system memory (unless you have masses of it) will be gobbled up by the OS (mostly for 'top' "buff/cache"). For the most part you can consider "buff/cache" to be disk buffers - uncommitted disk writes but the OS will not return it to "avail Mem" unless it has to. It's not very important if "avail Mem" is getting smaller if (loosely) "buff/cache" is getting larger and vice-versa.
Things will slow to a crawl should "Swap" start growing. In a scenario where you happen to be watching, if you see "avail Mem" getting low then next to shrink will be "buff/cache" as the OS hands back buffers to "avail Mem". If both get low, the system will start paging and "Swap" will grow. You can use the command 'swapon -s' to get paging information on its own.
One of the major problems with a suddenly sluggish system is trying to log it masks the issue by virtue of attempting to log it. It can be useful to 'ssh' in from another box so logs don't get written to the problem box.
Things will slow to a crawl should "Swap" start growing. In a scenario where you happen to be watching, if you see "avail Mem" getting low then next to shrink will be "buff/cache" as the OS hands back buffers to "avail Mem". If both get low, the system will start paging and "Swap" will grow. You can use the command 'swapon -s' to get paging information on its own.
One of the major problems with a suddenly sluggish system is trying to log it masks the issue by virtue of attempting to log it. It can be useful to 'ssh' in from another box so logs don't get written to the problem box.
Statistics: Posted by swampdog — Fri May 16, 2025 9:09 pm