Swap and RAM consumed in MySQL dump process

[mnbvmnbv]

Hello,

I have a slave instance of MySQL and every night ram and swap is very high.
The problem is that the pages that is in the swap , after the dump process, theses not move to RAM.



This is a free -m of the situation :

free -m
total used free shared buffers cached
Mem: 24081 23800 280 0 101 1086
-/+ buffers/cache: 22613 1468
Swap: 8001 5254 2746



This is the sar -W output:

sar -W
Linux 2.6.18-238.12.1.el5 (eul3300302) 31/08/11

00:00:01 pswpin/s pswpout/s
00:10:01 527.74 330.39
00:20:01 557.70 368.51
00:30:01 612.07 321.85
00:40:01 634.91 336.79
00:50:01 554.84 136.83
01:00:01 489.25 263.37
01:10:01 91.27 40.12
01:20:01 124.49 0.00
01:30:01 12.05 25.58
01:40:01 7.76 0.00
01:50:01 14.70 0.00
02:00:01 5.32 0.00
02:10:01 9.60 0.00
02:20:01 3.94 0.00
02:30:01 7.78 0.00
02:40:01 5.07 0.00
02:50:01 4.00 0.00
03:00:01 8.39 3.94
03:10:01 625.21 184.37
03:20:01 727.96 221.81
03:30:02 802.06 281.02
03:40:01 627.59 168.00
03:50:01 608.68 182.19
04:00:01 98.26 43.71
04:10:01 12.96 1.29
04:20:02 16.43 3.71
04:30:02 13.03 5.50
04:40:01 10.05 0.54
04:50:01 27.58 5.34
05:00:01 6.09 12.24
05:10:01 5.90 0.00
05:20:01 4.29 0.00
05:30:02 3.36 0.00
05:40:01 5.55 0.00
05:50:01 8.61 0.00
06:00:01 4.76 9.52
06:10:01 34.49 0.00
06:20:01 3.28 0.00
06:30:01 2.33 0.00
06:40:01 3.30 0.00
06:50:01 2.22 0.00
07:00:01 2.49 0.00
07:10:01 5.58 416.19
07:20:01 3.41 0.00
07:30:01 3.12 0.00
07:40:01 1.22 0.00
07:50:01 2.85 0.00
08:00:01 1.18 0.00
08:10:01 12.01 0.00
08:20:01 0.90 0.00
08:30:01 0.47 0.00
08:40:01 0.44 0.00
08:50:01 0.92 0.00
09:00:01 0.50 0.00
09:10:01 7.11 0.00
09:20:01 202.85 0.00
09:30:01 0.25 0.00
09:40:01 25.39 0.00

09:40:01 pswpin/s pswpout/s
09:50:01 2.16 0.00
10:00:01 0.98 0.00
10:10:01 14.79 0.00
10:20:01 2.41 0.00

Average: 120.91 53.39


I can restart the service, but the day after it will be happend.

thanks in advance

[Lazydog]

The problem is that the pages that is in the swap , after the dump process, theses not move to RAM.

And that is how it should be. What is in swap is not in use presently and once it is needed it will be read back into memory.

If I am not mistaking what is written to swap isn't removed when it is read back into memory.