[CentOS] Calling All FS Fanatics

Thu Oct 5 04:05:52 UTC 2006
Feizhou <feizhou at graffiti.net>

> I finally figured out my slowdown problem: I had somehow turned off 
> write-caching on the 3Ware controller. Hoo-Boy! Does that kill 
> throughput! What the heck is that option for anyway?

For cases where you do not want to lose your data when you get a 
blackout. If you do not have a battery power backup for your cache, you 
will lose data that is in the cache that has not been committed to the 

> Here are a handful of bonnie++ benchmarks, I decided to just quote the 
> block write and block read numbers:
>         MB/Sec
>         Write   Read
> XFS:    231     202
> ext2, dir_index:
>         221     205
> ext3, dir_index, data=ordered:
>         80      196
> ext3, dir_index, data=writeback:
>         95      199
> ext3, data=writeback:
>         95      201
> As you hinted, ext2 has almost the same performance as XFS. 
> Data=writeback on ext3 helps some but not a whole lot. Dir_index doesn't 
> seem to do a thing.

Indexes directories are only useful for cases where there are thousands 
of files in a directory and you want to access a single file (and you 
know the name in advance) quickly.

> I'm really torn here. I can make use of the extra write speeds of ext2 
> or XFS. But is XFS stable and supported enough for 'production' use? 
> Will I regret a forced fsck on a 1TB ext2 volume?

Are you using the no write cache flag with bonnie++? Otherwise you may 
not get the same results from whatever it is that you are running.

> Steve, you say you've been happy with XFS for a few years. Have you been 
> using it under any kind of load?

Run XFS without write caching and you should be safe. Are you creating 
thousands of files?