[Gluster-users] Interesting experiment

[Liam Slusser]

On Tue, Aug 18, 2009 at 3:05 AM, Hiren Joshi<josh at moonfruit.com> wrote:
> Hi,
>
> Ok, the basic setup is 6 bricks per server, 2 servers. Mirror the six
> bricks and DHT them.
>
> I'm running three tests, dd 1G of zeros to the gluster mount, dd 1000
> 100k files and dd 1000 1M files.
>
> With 3M write-behind I get:
> 0m35.460s for 1G file
> 0m52.427s for 100k files
> 1m37.209s for 1M files
>
> Then I added a 400M external journal to all the bricks, the twist being
> the journals were made on a ram drive....
>
> Running the same tests:
> 0m33.614s for 1G file
> 0m52.851s for 100k files
> 1m31.693s for 1M files
>
>
> So why is it that adding an external journal (in the ram!) seems to make
> no difference at all?

I would imagine that most of your bottle neck is with the network and
not the disks.  Modern raid disk storage systems are much quicker than
gigabit ethernet.

liam