Re: More than 2 Gb of swap

Hi,

On a system with Linux RedHat AS 3.0 (kernel 2.4.21-20.ELsmp) with an
AMD Opteron, I have got 4 GB of RAM and 8 GB of swap. These 8 GB of
swap are on only one partition.

According to the man of mkswap (The maximum useful size of a swap area
now depends on the architecture. It is roughly 2GiB on i386, PPC,
m68k, ARM, 1GiB on sparc, 512MiB on mips, 128GiB on alpha and 3TiB on
sparc64).
This rule imposes 4 partitions of 2G to have 8 GB.

I have conducted the following test:
I have disabled the swap partition and created 4 swap files of about 2
Gb each.
The snmp information for the total swap is still wrong (2 Gb instead of
8 Gb). The top stills seem to be ok.

# snmpwalk -c public -v 1 127.0.0.1 1.3.6.1.2.1.25.2.3.1.5.102
HOST-RESOURCES-MIB::hrStorageSize.102 = INTEGER: 2097151
# snmpwalk -c public -v 1 127.0.0.1 1.3.6.1.2.1.25.2.3.1.6.102
HOST-RESOURCES-MIB::hrStorageUsed.102 = INTEGER: 146528

# cat /proc/swaps
Filename Type Size Used
Priority
/sysout/test_swap1 file 1999992 146500 -2
/sysout/test_swap2 file 1999992 0 -3
/sysout/test_swap3 file 1999992 0 -4
/sysout/test_swap4 file 1999992 0 -5

Top:
Swap: 7999968k av, 145484k used, 7854484k free 2384872k cached

I assume that information given by 'top' is correct while information
given by snmp is wrong. Moreother, I assume that contrary to the man of
mkswap, I can use a swap partition of more than 2 Gb. If you have
contrary information, I'm interested in.

Sylvain

.

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