[mythtv-users] Fine-tuning NFS parameters
belcampo
belcampo at zonnet.nl
Sat Jul 24 07:29:28 UTC 2010
Gavin Hurlbut wrote:
> On Fri, Jul 23, 2010 at 4:56 PM, Kevin Ross <kevin at familyross.net
> <mailto:kevin at familyross.net>> wrote:
>
> On 07/23/2010 04:21 PM, Gavin Hurlbut wrote:
>
> But for a minimum, on the client side, mount with options:
> soft,posix,bg,intr,rsize=32768,wsize=32768,nfsvers=3
>
>
> I looked up your mount options. It seems some are not necessary,
> and at least one is deprecated.
>
> soft: not performance related, personal preference on hard vs. soft.
>
> posix: couldn't find a reference in my man page
>
> bg: not performance related, personal preference on fg vs. bg.
>
> intr: deprecated
>
>
> Not deprecated in my man page.
>
>
>
> rsize/wsize: The "TRANSPORT METHODS" section of the man page says
> you should specify rsize and wsize when using UDP, not when using
> TCP. And all modern NFS implementations use TCP.
>
>
>
> nfsvers: autonegotiated to 3 if both sides support it, otherwise 2.
> So this seems unnecessary also.
>
>
> If your NFS server doesn't require the options, great. However... If
> it does NOT, you should do it...
>
> nfsvers=3 is a minimum. If both sides do not support 3, you want the
> mount to FAIL. NFSv2 does not support files > 2GB in size, making it
> absolutely useless for mythtv recordings.
>
> As for the rsize/wsize... I don't care what your man page indicates,
> those are the parameters to tweak for performance in NFS. If your setup
> defaults to good settings, great. I would not presume that "all
> modern...." means squat. I have seen "modern" NFS implementations that
> use UDP, and that require the options stated.
>
> The *default* rsize/wsize for many NFS servers is 4k. This sucks really
> badly for performance, especially on GigE.
>
>
> Gavin, I don't mean to be picking on you. I just wanted to see if
> those options were better than sticking with defaults. So I looked
> up the options you recommended, but it seems those might not be
> ideal, either.
>
>
> OMG. If you want "ideal", then you'd better start running bonnie and
> get tweaking for your system.
mythtv and bonnie are quite opposite applications. Reading large
multimedia-files and reading/writing database-fields. What's good for
one is really bad for the other.
The default for 'current' kernels are 1M for both r and w.
All nfs blocksizes have gone up over the last years and for a reason.
I myself use a special-kernel with 2M blocksizes.
>
>
> Also, the "async" option I recommended appears to only apply when
> writing to an NFS mount, not reading from it. Since the OP will
> presumably only be reading from NFS, async mode probably won't buy
> him anything. So sticking with the defaults will probably be
> perfectly fine.
>
>
> Possibly. Another useful one: proto=tcp (or proto=udp) (or simply tcp
> or udp).
>
> Anyways, go ahead and play to your own satisfaction :)
>
>
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>
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