[wellylug] Debian & NFS

[Geraint Jones]

iSCSI looks like a good emerging option - I use it on a big storage
array used by 3 boxes to share the same oracle DB using RAC

http://www.cuddletech.com/articles/iscsi/

it will allow you to export a disk on one machine and use it on another
where it differs from NFS etc, is that its disks show up as true block
devices - eg /dev/sda1

this has numerous benefits. However it may well be overkill for what you
want to do.

Geraint 


-----Original Message-----
From: wellylug-admin at lists.wellylug.org.nz
[mailto:wellylug-admin at lists.wellylug.org.nz] On Behalf Of Ewen McNeill
Sent: Wednesday, 6 July 2005 7:15 p.m.
To: wellylug at lists.wellylug.org.nz
Subject: Re: [wellylug] Debian & NFS 

In message <Pine.LNX.4.61.0507061836250.29314 at localhost>, David Antliff
writes:
>Does anyone know what the Real Deal is with the *two* NFS servers in 
>Debian? There's nfs-user-server and nfs-kernel server. 

nfs-user-server is entirely implemented in user space.
nfs-kernel-server is just a front end to the in-kernel NFS server which
arrived (IIRC) in either the 2.2 or 2.4 kernels (although it isn't
always
compiled in).  From memory nfs-user-server has been in Debian (called
something like nfs-server originally) since the 1.x Linux kernels).

Generally I'd say use nfs-kernel-server if your kernel has support for
it.
It should be faster (fewer context switches), and as you've found there
are various issues with the nfs-user-server implementation (including
that it apparently isn't compiled with the large files options
available/turned on).

>User xyz has uid 1000 on hostA, but uid 1001 on hostB. HostA exports a 
>directory and user xyz on hostB can't access it properly because of the

>uid mismatch. 

Welcome to NFS.  The traditional solution is to synchronise the uids on
all the hosts to match, either by hand (eg, /etc/passwd pushes) or
through some sort of directory system (NIS, LDAP, etc).  For a tiny
network I generally do it by hand; on larger networks I've used both NIS
and LDAP successfully.

FWIW, these days I'd probably be pretty tempted to use Samba and the
CIFS
client built into the kernel (2.6 kernels anyway; I think there's a
patch
for 2.4).  Particularly with the unix extensions (supported by both)
it should be a fairly good solution.  (Not sure how the performance
would compare with the nfs-kernel-server, possibly a little slower,
but that may not matter to you.)

>Does Samba still have a 2GiB file size limit?

I believe Samba 3 (eg, in Debian Sarge) is generally built with large
file support enabled, and I think the in-kernel CIFS client should
support large files.

>Are there any other alternatives to NFS worth looking at?

AFS (eg, OpenAFS) might also be worth a look.

Personally I still use NFSv3, in kernel, and sync uids by hand.

Ewen


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