gmirror performance

[Ivan Voras]

On 17 March 2011 07:57, Marcus Reid <marcus at blazingdot.com> wrote:

>
> Wow, that's great.  I just almost doubled big sequential read performance
> on one of my machines with this too.  The question now is why the defaults
> are the way they are...  Does a big vfs.read_max (described as "Cluster
> read-ahead max block count") pessimize performance in some other way?

Note that it will only help sequential reads. If you have a database,
e-mail server or any other random IO load, it will not help you one
bit. On the other hand, it will also not harm performance in that type
of environments.

It's an old tunable which has not been properly investigated ever
since it was last modified 10 years ago; this and few other obscure
file system tunables (hi/lo runningspace, dirhash_maxmem) will be much
more sanely tuned for 9.0.