SUMMARY: swap partition

Date: Tue Dec 16 1997 - 04:06:44 CST

thank you for all responses. Thanks a lot to

My original question is below. Some answers differ at some points. But
generally the followings are results. I worked with HP and DEC systems.
They advised me that swap partition should be at least 2xphysical memory or
 more. So I thought like this and decided 1 GB swap partition.
Of course if swap is used so frequently I will add more memory to system.

- One big partition should be better than several smaller ones. But If you
 require this much swap, maybe adding more RAM would be a
better option

- Thank you Birger for giving the information of mirrored swap partition.
 If you are running mirrored system disks, you could either use mirrored
swap as well (a performance hit for writing to swap), or run two
identical non-mirrored swap partitions on the two disks. If running with
two swap partitions, you get twice the amount of swap, better
performance, as Solaris will distribute swap over 2 disks, but a disk
failure will yield a panic/reboot. There should be no data los iff
else is mirrored.

- Swap will be quicker if it is done to multiple swap partitions on
separate spindles.

- Dan's answer confused me. But he gives an web site for more information.
Thanks again.

solaris doesn't require to have 2xRAM for swap space. Unless your
applications require that much swap you can get away with
1XRAM for swap space. Disk performance would depend on how often your swap
space is accessed. If it is not accessed often
then you can keep it on one disk. If it is accessed a lot, then it is
better to stripe the swap across many disks.
Check out:

and get the SE toolkit that the article describes and learn to use it.

- I am not sure if you have 2x2.1GB HD on each of the 450 server. For
better performance, you may create one partition on each of the disk,
which means creating a 500 MB swap partition on each of your 4GB HD.
Or create one 1GB swap partition on one 4GB disk, but you got to check the
disk I/O to find the one with less traffic.
I use a 2GB disk as a swap disk on a Ultra1 to free up my system disk and
get faster speed for runnig Image analysis applications.

My original question;


I need an advice. We have new 2xSUN 450 servers with 2xCPU and 512 MB
memory and 4 GB system disk mirrored. One of them is application server
and other is database Oracle server. I am planning to create 1 GB of swap
parttion on system disk. But I am not sure that whether I should create all
partion on 1 and system disk from the performance point of view. Actually I
am planning to create this 1 GB partition on the system disk and if I need
more swap partition to add from one of other disks. Am I right? If you
think that it must be summarized I will. Thank you in advance.


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