Date: Fri, 5 Aug 2016 08:11:11 -0600 From: Alan Somers <asomers@freebsd.org> To: Daniel Genis <daniel.genis@gmx.de> Cc: FreeBSD <freebsd-stable@freebsd.org> Subject: Re: zfs recv causes nfs server to throw NFSERR_IO i/o errors Message-ID: <CAOtMX2j2DRNW87XypXNDs17e838EhPtUhX2OZJq2X5QSOb731A@mail.gmail.com> In-Reply-To: <1df33129-0c3e-dfc3-6867-46ab0473ae57@gmx.de> References: <1df33129-0c3e-dfc3-6867-46ab0473ae57@gmx.de>
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On Fri, Aug 5, 2016 at 7:22 AM, Daniel Genis <daniel.genis@gmx.de> wrote: > Hi everyone, > > we've been tracing an issue where snapshot replication is causing > interruptions for the NFS serivce. > > The problem is as follows: > > Every time a zfs recv finishes, there is a chance for the NFS server to > return an NFSERR_IO for a GETATTR call. This shows up as input/output > errors on the nfs clients. > > Here the tcpdump showing the NFS conversation: > https://nopaste.me/view/95d1a79d > > NFS 202 V3 GETATTR Call (Reply In 6043), FH: 0x8c711a60 > NFS 98 V3 GETATTR Reply (Call In 6042) Error: NFS3ERR_IO > NFS 222 V3 LOOKUP Call (Reply In 6046), DH: 0x6694634f/example.file.txt > NFS 102 V3 LOOKUP Reply (Call In 6045) Error: NFS3ERR_ACCES > > We've been able to verify that there is a _direct_ correlation between > the zfs recv command and these NFS errors. For every input/output error > we can find a log entry of a replication just finishing (zfs recv exiting). > > The receiving server is running 10.3-RELEASE > > I've read about a VFS/ZFS deadlock issue which is to be included/fixed > in Freebsd 11.0-BETA4. > > Could our issue be related? > Otherwise does anyone have any suggestions how to tackle this issue? > > > For the record, say we have two volumes: > tank/volumeA and tank/volumeB > > If there is a zfs recv busy for tank/volumeA then tank/volumeB can get > these NFS "io" errors, it does not have to be the same volume. > > > Has anyone else seen/experience this as well? > > Any insights are appreciated! > > With kind regards, > > Daniel Try adding mountd_flags="-S" to /etc/rc.conf.
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