Date: Mon, 1 Apr 2024 02:11:40 GMT From: Rick Macklem <rmacklem@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 71f16d2efe7e - stable/14 - nfsd.8: Document ways to minimize Copy operation times Message-ID: <202404010211.4312BepR090805@gitrepo.freebsd.org>
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The branch stable/14 has been updated by rmacklem: URL: https://cgit.FreeBSD.org/src/commit/?id=71f16d2efe7e9e6ba15620d5ecf6c22051feebfd commit 71f16d2efe7e9e6ba15620d5ecf6c22051feebfd Author: Rick Macklem <rmacklem@FreeBSD.org> AuthorDate: 2024-03-18 22:40:41 +0000 Commit: Rick Macklem <rmacklem@FreeBSD.org> CommitDate: 2024-04-01 02:10:40 +0000 nfsd.8: Document ways to minimize Copy operation times For NFSv4.2, a Copy operation can take a long time to complete. If there is a concurrent ExchangeID or DelegReturn operation which requires the exclusive lock on all NFSv4 state, this can result in a stall of the nfsd server. This patch documents ways to avoid this problem. This is a content change. (cherry picked from commit 8f13abb4fd2f3c5d25bde830607a4aec6cec42d9) --- usr.sbin/nfsd/nfsd.8 | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/usr.sbin/nfsd/nfsd.8 b/usr.sbin/nfsd/nfsd.8 index 0a9f6f82c85f..1c04bad3a042 100644 --- a/usr.sbin/nfsd/nfsd.8 +++ b/usr.sbin/nfsd/nfsd.8 @@ -27,7 +27,7 @@ .\" .\" @(#)nfsd.8 8.4 (Berkeley) 3/29/95 .\" -.Dd March 22, 2023 +.Dd March 16, 2024 .Dt NFSD 8 .Os .Sh NAME @@ -355,3 +355,25 @@ to be set to one on the MDS as a workaround. Linux 5.n kernels appear to have been patched such that this .Xr sysctl 8 does not need to be set. +.Pp +For NFSv4.2, a Copy operation can take a long time to complete. +If there is a concurrent ExchangeID or DelegReturn operation +which requires the exclusive lock on all NFSv4 state, this can +result in a +.Dq stall +of the +.Nm +server. +If your storage is on ZFS without block cloning enabled, +setting the +.Xr sysctl 8 +.Va vfs.zfs.dmu_offset_next_sync +to 0 can often avoid this problem. +It is also possible to set the +.Xr sysctl 8 +.Va vfs.nfsd.maxcopyrange +to 10-100 megabytes to try and reduce Copy operation times. +As a last resort, setting +.Xr sysctl 8 +.Va vfs.nfsd.maxcopyrange +to 0 disables the Copy operation.
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