Re: Separate file system for journal files - recommended size?

[Jenna deBoisblanc]

Hello Kim,

This recommendation is still valid.

On Sep 28, 1:16 pm, Kim <kxh...@gmail.com> wrote:
> We're thinking about using a separate file system for journal files and I'm
> wondering how to determine an adequate size.  I found a recommendation of
> 10 GB in the Notes section of this page:
>
> http://www.mongodb.org/display/DOCS/Journaling+Administration+Notes
>
> I'm wondering if it's still a valid recommendation and how the number is
> determined.
>
> Thanks,
> Kim

[Jason Koppe]

And the separate file system -- is that also recommended?  I'm not sure I see the benefit to having a separate file system if its on the same underlying disks.

[Adam C]

Realize this one is a bit stale, but to clear this up.  There is no requirement that you put the journal on a different filesystem, but it will prevent fragmentation of the journal and it will also mean that you don't have two different access patterns on the same single filesystem (most MongoDB data acces is a random pattern, while the journal is a sequential pattern).

If they are on the same disk you will see some small benefit thanks to the separation, but it will not be huge.  It is still a valid recommendation nonetheless.

Adam