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Is swap usage normal on an appliance?

elanmbx
Level 6

I've got several 5220s and when I check "top" on them I see that they are all using all available memory and are into swap.  I will be restarting these appliances in the near future so will be able to monitor this usage more closely, but in your experiences have your appliances tended to use up all their memory and get into swap space like this?

Granted - they aren't using a whole lot of swap (4-6GB), but these systems have 96GB of memory so I'm kind of surprised that there is any swap use at all.

Details:

5220 appliances running 2.6.0.2
74TB storage (64TB MSDP)
96GB memory

 

 

7 REPLIES 7

SymTerry
Level 6
Employee Accredited

Hello

Please refer to TECH184147 as this is expected behaviour. Are you seeing some sort of performance issue or just curious?

elanmbx
Level 6

I'm familiar with this sort of behavior in Linux - the thing is, with "normal" usage of all the memory in Linux there is NO swap use.  Once swap space starts getting used, there generally is some kind of issue.  Especially when talking systems with 96GB of memory.  If there was 0 swap use I wouldn't be concerned.

maintenance-!> free -m
             total       used       free     shared    buffers     cached
Mem:         96303      96057        245          0         18      49332
-/+ buffers/cache:      46705      49597
Swap:        66671       5259      61412
maintenance-!> 

 

elanmbx
Level 6

I'm familiar with this behavior in Linux - but it generally doesn't result in any swap usage.  The swap use is my concern.

I have been noticing what seem to be slower duplications/replications as of late, and that is what led me to this discovery...

SymTerry
Level 6
Employee Accredited

I checked with a Appliance SME and with 2.6, this is normal. If its 2.5 then soimething is going on. You may want to open a case. What version are you on? 

elanmbx
Level 6

2.6.0.2
 

SymTerry
Level 6
Employee Accredited

Then this is expected for the Swap. The slower deduplication as of late could be caused by many different things but no the swap.  Refer to the perfomance tuning guide DOC7449. This will give information on  how to calculate deduplication time, infomation, and perfomance consideration for deduplications. 

sdo
Moderator
Moderator
Partner    VIP    Certified
Hi - are you able to offer some background as to why this is now the normal expected behaviour in 2.6.x.x? Thanks.