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Date:      Wed, 4 Apr 2018 16:14:57 -0400
From:      Mike Tancsa <mike@sentex.net>
To:        Kaya Saman <kayasaman@gmail.com>, =?UTF-8?Q?Karli_Sj=c3=b6berg?= <karli@inparadise.se>, freebsd-fs@freebsd.org, Guido Falsi <mad@madpilot.net>
Subject:   Re: Linux NFS client and FreeBSD server strangeness
Message-ID:  <2937ffcc-6b47-91af-8745-2117006660db@sentex.net>
In-Reply-To: <4da08f8b-2c28-cf18-77d2-6b498004d435@gmail.com>
References:  <369fab06-6213-ba87-cc66-c9829e8a76a0@sentex.net> <2019ee5a-5b2b-853d-98c5-a365940d93b5@madpilot.net> <bc78744a-c668-cbbd-f6fd-0064e7f0dc46@sentex.net> <C3024CF7-3928-4DBF-9855-82451BDACE01@inparadise.se> <4da08f8b-2c28-cf18-77d2-6b498004d435@gmail.com>

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On 4/4/2018 4:04 PM, Kaya Saman wrote:
> I think I posted a similar topic ages ago but got no response. It would
> be interesting to see the cause for this. I have a hunch it could be
> something to do with the nfs implementation of Linux but it is just pure
> conjecture on my side.

I know what you mean about the zfs / zil lockups. It makes a HUGE
difference performance wise if you run with sync disabled on writes for
the zfs dataset. Not sure I want to do that. I am going to try later
with ZIL on some NVE devices and see I can have the best of both worlds.
 I have individual zfs data sets for each server to write their backups
to.  I might be able to live with the risk of running with sync disabled
to receive backup files with.

I think I may have found the setting on the LINUX client.  If I mount
with the options

-o tcp,intr,noatime,sync,vers=3

ie sync

I get the "smooth" traffic patterns. Its actually a bit slower than the
with the default async which I guess is able to burst up higher.

I am not sure how dangerous running async writes are on an nfs client.
But for now, this mystery seems to be a bit better explained to me!

	---Mike


-- 
-------------------
Mike Tancsa, tel +1 519 651 3400 x203
Sentex Communications, mike@sentex.net
Providing Internet services since 1994 www.sentex.net
Cambridge, Ontario Canada



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