[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-nfs
Subject:    Re: [NFS] Performance expectations of NFS
From:       Bernd Schubert <bernd-schubert () gmx ! de>
Date:       2007-01-25 22:50:21
Message-ID: 200701252350.22255.bernd-schubert () gmx ! de
[Download RAW message or body]

Hi Christian,

>   0:05  - Server: locally on RAID-5
>   0:06  - Client: copying from NFS mount to tmpfs
>   2:31  - Client: Copying from NFS mount to NFS mount
>           (i.e., the simple command above)
>   3:30  - Client: Copying from NFS mount to NFS mount over an existing
>           tree.
>   5:08  - Client: Copying from tmpfs to NFS mount
>   0:48  - Client: Deleting copy of tree on NFS mount

I guess your exports has the "sync" option or your didn't set  async or sync 
at all (sync is then the default)? Can you repeat the test again using the 
async option? But please, also read carefully the explanations of "man 5 
exports" about this topic. 

>
> Now I know that file creation is synchronous, and that because of this,
> the NFS copy will /always/ run significantly slower. But I was amazed at
> just how much faster reading was than writing, and at how fast reading
> actually is -- it's much faster than I expected NFS could be.

Just for fun, take ethereal and capture some data, once with the async and 
once with the sync option. Now have a look how much time each operation of 
the nfs client takes before it gets confirmed by the server. Especially look 
at the commit calls, once with sync and once with async option.

> But what I'd really like to know if there is a way of making the
> above operation run in significantly less time than it is today, or if

I guess if one could convince the nfs clients to reduce the number of commit 
calls, write operations would be much much faster. Don't know if that is 
possible at all, though.


Cheers,
Bernd


-- 
Bernd Schubert
PCI / Theoretische Chemie
Universität Heidelberg
INF 229
69120 Heidelberg


-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys - and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
NFS maillist  -  NFS@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/nfs

[prev in list] [next in list] [prev in thread] [next in thread]