samba - Jul 2004 - best filesystem choice for samba (was: new user cannotlogon)

ARGH!  I'm wondering if airing thoughts about VFAT performance publicly
was a good idea.

I was only interested from a technical point of view - I would NOT
recommend using it on a production server unless there happened to be a
real case for using it.

The biggest thing to bear in mind in your case is that VFAT does NOT
support ACLs or disk quotas.  It also doesn't support journalling and it
also has some strange case-sensitivity behaviour.

At the risk of sending someone else off on completely the wrong track,
how about we write ourselves our own FS specifically to give the best
possible performance for Samba?  ;)

Mark Lidstone
IT and Network Support Administrator

BMT SeaTech Ltd
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-----Original Message-----
From: Simon Oliver [mailto:s.oliver@umist.ac.uk] 
Sent: 08 July 2004 14:06
To: samba@lists.samba.org
Subject: [Samba] best filesystem choice for samba (was: new user
cannotlogon)


I am setting up a Samba server and am uncertain as to which filesystem
to choose.  

The consensus seems to be XFS but I'm not sure how proven this
filesystem is (I know SGI have used it since Irix 6.5 but that's a
different OS).

I want the filesystem to be available via both CIFS and NFS.

I need quotas and would like acls, but most of all want a fast reliable
system.

Reports indicate that ext2/3 is particularly slow, especially for long
file listings and many people complain have corruption issues with
reiser (nut maybe that's RedHat only).  Recently, someone even suggested
using VFAT!

I'd like to hear your thoughts and experiences with the various
filesystems, especially with regard to using them with Samba and/or NFS.

P.s. The filesystem will be on hardware RAID5, with a hardware RAID1
root filesystem.  I've heard that it makes sense to place the log file
on the RAID1 partition - I carried out some simple tests but couldn't
detect any difference in performance with XFS no matter where the log
file is.

-- 
  Simon Oliver

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Quoting Mark Lidstone <mlidstone@bmtseatech.co.uk>:
> ARGH!  I'm wondering if airing thoughts about VFAT performance publicly
> was a good idea.
I doubt VFAT's case insensitivity would be worth dealing with its terrible
linear-search-time directory lookup methods.

The reason I suggested reiserfs (or ext3 with directory hashing) is to
reduce the high costs of locating a directory entry within a directory of
many (> 10,000) files.

msdos/vfat does not offer superior directory lookup times, and from my
limited testing, neither does NTFS.

ext2/ext3 in stock configuration is also slow, though it appears very recent
kernels/ext2fsutils offer an FFS-like "directory hashing" option which
needs
a format-time decision to be made upon setting up the filesystem.

I have no knowledge about XFS or JFS and how they compare.  I know both are
"industrial" filesystems brought down from the Ivory Towers onto the
pipsqueak platforms.

As for "horror stories", well, each filesystem has had their
respective
tales of misery and woe... ext3 had shocking and fatal dataloss bugs in the
adolescent versions of 2.4.x., and some RAID + reiserfs configs saw some
real wowsers as well.  From bug reports/changelogs, I've seen similar tales
of woe for XFS and JFS if you trigger just the right combination of things.
>From my own experiences, things have matured and stabilised with reiserfs
and ext3 to the point where using either is fine for my purposes.

The decision comes down to:

1) Do you need quotas?  If yes, you cannot use reiserfs.
2) Do you need ACLs?  If yes, only ext2/ext3 has well-tested seamless
support, though I think there are wildcat patches to bring this to XFS (and
maybe others) as well.  I'm not sure about the stability of this.

ext3 used with -O dir_index *MAY* provide better performance for large
directory list lookups, but I've never tested it.  It requires Linux 2.6 for
starters for the kernel-side stuff to actually support it properly. 
grepping the linux 2.4 source shows no mention of hashing b-trees or
dir_index options for ext[23].

This is a RECENT addition to ext3, and I don't think the support actually
exists within 2.4 yet.  I've seen mention of "special backported
patches"
but this smells scarier to me than using filesystems which have been
seamlessly integrated for over a year or so now.

So in terms of viable performance-driven alternatives, I see it being
reiserfs, xfs, or jfs.

vfat/dos isn't faster, even with case insensitive semantics, for directory
sizes of 20,000 or more.

=MB=