How to increase the swap memory for mysql in centos 6.2

jsaravana87 · 06-14-2012, 03:32 AM

Hi all,
One of my centos machine i want to increase of swap memory for mysql .

Quote:

[root@example ~]# vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
1 0 537016 77028 14096 188032 38 43 102 61 108 316 1 1 97 2 0

Quote:

[root@example ~]# sudo dd if=/dev/zero of=/mnt/file.swap bs=1M count=512

512+0 records in
512+0 records out
536870912 bytes (537 MB) copied, 2.78301 s, 193 MB/s

Quote:

[root@example ~]# mkswap /mnt/file.swap
mkswap: /mnt/file.swap: warning: don't erase bootbits sectors
on whole disk. Use -f to force.
Setting up swapspace version 1, size = 524284 KiB
no label, UUID=f2612905-e880-48b1-ae65-13dc93f101ce

Quote:

[root@example ~]# sudo swapon /mnt/file.swap
[root@example ~]# vi /etc/fstab

Quote:

[root@example ~]# fdisk -l

Disk /dev/sda: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000b6c32

Device Boot Start End Blocks Id System
/dev/sda1 * 1 39 307200 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 39 6271 50056192 83 Linux
/dev/sda3 6271 6528 2064384 82 Linux swap / Solaris

Quote:

[root@example ~]# free -m
total used free shared buffers cached
Mem: 993 926 66 0 2 198
-/+ buffers/cache: 725 267
Swap: 2527 523 2004

Quote:

[root@example ~]# vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
0 0 535968 68376 2928 202980 38 43 102 68 108 317 1 1 97 2 0
[root@example ~]#

syg00 · 06-14-2012, 04:32 AM

And ... ?

jsaravana87 · 06-14-2012, 04:43 AM

Hi

Im trying to increase the swap memory for my mysql alone.whether its possible to allocate large amount of virtual memory to my mysql application . Tomcat i had increase the virtual memory by using following command in service export JAVA_OPTS="-Xms128m -Xmx512m" .In same way whether i can determine my mysql application to utilise lareger virtual memory at startup of mysql

syg00 · 06-14-2012, 05:57 AM

Not directly - the system handles that automatically. Large memory users will (typically) use the swap most - if they actually use ("dirty") the memory.
In general, everything is done not to use swap - it's too slow compared to RAM.