Re: [BackupPC-users] NAS performance over NFS

[Les M. <les...@gm...>]

Tino Schwarze wrote:
> On Tue, Sep 02, 2008 at 11:34:44AM +1000, Stephen Vaughan wrote:
>> Hmm yeah I've a bit of a play with the nfs client side, the nfs server is
>> purely web based, so it's limited to what I can play with.
>>
>> What about the network side of things, with data coming in and back out on
>> the same interface?
> 
> I's say: Tune NFS performance first without backuppc - you probably need
> to tune NFS anyway. Then look how it works. Separating the interfaces
> might be a good idea, but on the other hand, the access should be rather serial:
> 
> - server receives something via rsync protocol
> - then reads or writes some data via NFS
> - then sends response to client
> 
> Situation is a bit different with multiple concurrent backups. If it's
> cheap to add another NIC, just do it - but it might not solve your NFS
> performance issues.

The main things likely to matter are the mount options for read/write 
block sizes and sync vs. async.  With sync, every operation on the 
client waits for completion on the server so it is much slower than 
local disks where these will be buffered.  With async, you have a chance 
of losing data that a program thought was committed to disk if you lose 
power - but it's a backup so it's like losing power a minute earlier...

-- 
   Les Mikesell
    les...@gm...