Friday, October 14, 2005

Disk performance

UNIX Museum wrote:
> Hi there,

> I am trying to understand why my SB1K gives me abysmal performance on
> sequential read/write...

> So, it appears to me that the culprit is the scratch filesystem... I
> tried to mount the drive with forcedirectio, but it looks like it made
> things even worse... Does anybody have any suggestion?

Yepp, forcedirectio is for databases that do their own caching.

If you are doing verylargefiles you should :

1. make the filessystem with fragsize set equal to blocksize
2. set cylinder group size to 32.
3 set the "maxbpg" to 50% or 99% of the amount of blocks
in a cylinder group

Look at fstyp(1M) and tunefs(1M) and newfs(1M)

//Lars

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