swap space

[zach]

In a recent conversation with a SUSE SLES support representitve, he explained to me that my server, which has 4GB of RAM, shouldn't need any more than a 1GB swap partition. Does Scalix require me to setup the server with the traditional 2xRAM configuration? 8GB of swap space seems like an overkill.

[jch]

There's some disagreement about how much swap you should have. At one extreme there's the twice physical memory and at the other extreme there's none at all (when you've ot loads of memory).

How much you actually need depends on how much virtual memory you're using. If you're using less virtual memory than you have physical then you don't need much swap. One school of thought says that you ought to have at least a little bit as it gives the VM subsystem some headroom, but on some kernels (notably 2.4, but someone claimed 2.6 as well) having any swap at all on a very large memory system caused problems.

I would be inclined to go with the recommendation, but keep an eye on system performance. if you're seeing swap space actually being allocated then re-visit the amount you've got configured: if you're using LVM (and I hope you are) then adding more swap space is easy.

There's certainly nothing inherent in Scalix that means that we want more (or less) configured swap space; we're just a fairly big application doing a lot of I/O.

jch

[jch]

Sigh. Eyes not all they should be today. I meant to say, that I'd go with the 1GB recommendation and see how it goes.

jch

[zach]

The Scalix Knowledgebase article for configuring the Logical Volume Manager doesn't include swap space in the LVM. It limits the LVM to /var/opt/scalix, while creating separate partitions for /, /boot, and swap. Is there any danger in adding partitions such as these to the LVM?

[jch]

Absolutely not. The recommended configuration -- the default anyway -- for RHEL4 and Fedora Core 4 puts everything apart from /boot under the control of the logical volume manager. The only problem I've ever had is that software suspend doesn't work for me using a logical volume for swap.

jch