[aclug-L] Re: Dual swap partitions

[Jonathan Hall <jonhall@xxxxxxxxxxxxxxxxxxxxx>]

> 1) How do I go about getting Linux to recognize and use both partitions for
> swap?

This one has already been answered, so I won't answer it again..


> 2) Are there any performance differences for using two swap partitions as
> opposed to using only one?

My understanding here is... if the partitions are on DIFFERENT PHYSICAL
DISKS... you will actually IMPROVE performance, as the Linux kernel will
automatically do what is essentially RAID0 between the two (or more) swap
partitions.  In other words, it will use both partitions at the same time,
thus increasing disk access time (it can read or write to both at the same
time, rather than waiting for one to finish before it goes to the other
partition).

If they are on the same physical disk, you should see no degredation of
performance...

Note, however, that you can improve perfomance by putting swap partition(s)
near other frequently accessed portions of the disk.  I used to put my swap
partition at the end of my hard drive for convenience... I've learned this
is silly =)

Now I usually put my swap partition immediately before my /usr partition, so
that the heads have a shorter distance to travel between the frequently
accessed /usr and the swap partition.  With the swap partition at the end
(and /usr at the beginning), the heads would have to travel nearly the
entire distance of the disk surface between swap I/O and /usr I/O.

Just a couple considerations there... :-)


--
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