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5230: Excessive swap usage?

elanmbx
Level 6

Just wanted to see what others' experiences might be regarding swap usage on their appliances - I have one *very* busy appliance which recently was exhibiting performance issues... and upon investigation I saw that there was over 30GB of swap in use (of 64GB configured).

Upon investigation of my other appliances, I do see swap in use, but it is quite a bit lower (10-12GB).

I'm actually pretty surprised that there is *any* reported swap in use, since there always seems to be a bit of free memory reported on each of the appliances.

5230 Media Servers, Appliance Version 3.0

21 REPLIES 21

This continues to be an issue.  One thing that I do notice, which seems to point to the swap usage *actually* being a problem:

When the appliance is super-busy and swap use is high, I  can see the "kswapd0" proess up near the top of the "top" monitoring utiltiy.  Which seems to indicate that this swap issue is very likely causing performance issues on this appliance.

I think I'll try opening another case and see if I can get a fresh set of eyes on it...

My suspicion is that my dedupe fingerprint cache in memory is simply too high - and, when combined with a lot of backup jobs, exceeds the physical memory (128GB) and the continuous swap eventually starts causing performance issues.

It seems, invariably, that when I restart NBU services & Infrastructure Services (just for good measure) the issue goes away - sometimes for a few days, sometimes just for a day... but it gets better, however long it lasts...

I've concluded that this is *definitely* an insufficient memory issue.  I am pursuing a memory upggrade for one of my 5230s and my 5240.  Vmstat output is pretty conclusive:

5230:

procs -----------------------memory---------------------- ---swap-- -----io---- -system-- --------cpu--------
r b swpd free buff cache si so bi bo in cs us sy id wa st
7 11 11076164 1444776 10972 22719840 137 95 2776 817 8 0 6 8 72 14 0
13 11 11069980 999956 10144 23026748 1324 0 451279 73731 96299 141767 29 19 34 18 0
14 14 11066912 1399628 9224 22484272 570 0 383975 82551 100719 141763 29 17 36 18 0
12 12 11066528 1404960 9204 22456372 105 0 356733 78383 93251 132844 28 14 38 20 0
10 13 11061960 1212244 8956 22565576 1847 0 358394 96607 96175 129575 28 14 39 20 0

5240:

procs -----------------------memory---------------------- ---swap-- -----io---- -system-- --------cpu--------
r b swpd free buff cache si so bi bo in cs us sy id wa st
7 9 31416100 17239564 4428 12056340 64 27 5941 1450 0 0 8 14 62 16 0
0 6 31410804 16763312 4492 12484952 7740 0 132268 35708 72040 79947 3 3 75 19 0
0 5 31409760 16881020 4488 12317944 8433 6 59214 2964 61446 63671 1 15 69 15 0
27 7 31414608 16642612 4408 12487944 7782 34 134742 5080 113575 77210 2 20 65 13 0
46 5 31397484 16934808 4400 12136004 4898 173 59308 26382 108851 25703 5 86 6 3 0
33 3 31396448 17190940 3208 11944984 1807 19 67534 47999 80462 60340 6 81 8 5 0
29 3 31396372 17437076 2608 11677792 1102 0 41491 15577 92243 94953 4 83 9 5 0