Date: Fri, 5 Aug 2016 16:54:49 +0200 From: Daniel Genis <daniel.genis@gmx.de> To: Alan Somers <asomers@freebsd.org> Cc: FreeBSD <freebsd-stable@freebsd.org> Subject: Re: zfs recv causes nfs server to throw NFSERR_IO i/o errors Message-ID: <1eb419ed-4180-11c2-3bf3-5d3013a07197@gmx.de> In-Reply-To: <CAOtMX2j2DRNW87XypXNDs17e838EhPtUhX2OZJq2X5QSOb731A@mail.gmail.com> References: <1df33129-0c3e-dfc3-6867-46ab0473ae57@gmx.de> <CAOtMX2j2DRNW87XypXNDs17e838EhPtUhX2OZJq2X5QSOb731A@mail.gmail.com>
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Thank you, that probably is what the doctor ordered! My quick testing shows that it's very likely fixed. Kudos! :-) On 08/05/2016 04:11 PM, Alan Somers wrote: > 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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