Re: Choosing and tuning Linux file systems

[Matthew Wilcox <matthew@wil.cx>]

On Sun, Jun 25, 2006 at 03:00:53PM -0700, Valerie Henson wrote:
> I foolishly signed up to give a talk at OSCON in about a month about
> choosing and tuning Linux file systems for different workloads.  I
> 
> Laptop: ext3 with noatime
> General purpose server: ext3 or reiser
> Lots of small files: reiser, ext2/3 with 1k blocks
> More than ~32,000 files in one directory: XFS or reiser
> Fast lookups in large directories: XFS, reiser, ext3 with htree (?)
> File size more than 2TB: XFS, reiser up to 8TB
> File system size more than 2TB: XFS, reiser up to 16TB
> Ease of data recovery after corruption: ext2, ext3

An interesting workload you don't cover here is the PVR workload.
You're looking at lots of 1-2GB files (1GB for half-hour programs, 2GB
for full-hour).  Reads and writes are sequential; overwrites and random
accesses almost never happen.  It's not uncommon (at least for those of
us with two tuners ...) to record two things while watching a third,
so support for massive preallocation will prevent fragmentation.
All these files are in one directory (so ext2/3's Orlov allocator is
pretty much defeated).

> Tuning a file system
> 
> Use "noatime" mount option
>  - atime makes read workloads into random write workloads, yuck
>  - This is Ubuntu installation default
>  - I have a report that mutt doesn't work with this because atime is
>    never updated but mtime is, maybe some kind of lazy atime is better?
>  - Don't do if you want to e.g., track down hackers

Mention nodiratime?