Quote:
Originally Posted by
TinWalrus
i think the best way to do this is to have part of your paging on rootvg (memory*2) which is mirrored (or should be) then have an additional non-mirrored disk for additional paging space[...]
Well... Let's look at an example: my server has 48GB of RAM so my paging space should be as big as 96GB?
Let's have a look at shockneck's top four tips about AIX paging space:
1) If AIX uses paging space you lack RAM or/and you configured vmo wrong. If tuning cannot help anymore get more RAM chips. Best thing is not to use paging space.
2) There is no such thing as an "official" recommendation about how big paging space should be (beside some application vendors such as SAP and/or your app's allocation policy) for many years now. Default settings for AIX have become pretty small since AIX 5L. Paging space shall be as big as necessary but as small as possible. I.e. it depends on how you use the server.
3) If AIX uses paging space it stores data that does not fit into RAM (and is not stored on disk already). Thus losing paging space is equivalent to losing a memory chip. Hence if you don't mirror it the other (SAN) storage should be at least as safe as it would be on mirrored disks.
4) If you use several paging spaces keep them at about the same size. If you want to you can make hd6 slightly bigger as it is used during boot. Furthermore speed of different disks used for paging should not differ to a large extend. Don't use two or more paging spaces on the same disk.