From: Tom Talpey <tom@talpey.com>
To: NeilBrown <neilb@suse.com>, Olga Kornievskaia <aglo@umich.edu>,
Chuck Lever <chuck.lever@oracle.com>,
Schumaker Anna <Anna.Schumaker@netapp.com>,
Trond Myklebust <trondmy@hammerspace.com>
Cc: linux-nfs@vger.kernel.org
Subject: Re: [PATCH 0/9] Multiple network connections for a single NFS mount.
Date: Thu, 30 May 2019 13:05:04 -0400 [thread overview]
Message-ID: <1df23ebc-ffe5-1a57-c40a-d5e9a45c8498@talpey.com> (raw)
In-Reply-To: <155917564898.3988.6096672032831115016.stgit@noble.brown>
On 5/29/2019 8:41 PM, NeilBrown wrote:
> I've also re-arrange the patches a bit, merged two, and remove the
> restriction to TCP and NFSV4.x,x>=1. Discussions seemed to suggest
> these restrictions were not needed, I can see no need.
I believe the need is for the correctness of retries. Because NFSv2,
NFSv3 and NFSv4.0 have no exactly-once semantics of their own, server
duplicate request caches are important (although often imperfect).
These caches use client XID's, source ports and addresses, sometimes
in addition to other methods, to detect retry. Existing clients are
careful to reconnect with the same source port, to ensure this. And
existing servers won't change.
Multiple connections will result in multiple source ports, and possibly
multiple source addresses, meaning retried client requests may be
accepted as new, rather than having any chance of being recognized as
retries.
NFSv4.1+ don't have this issue, but removing the restrictions would
seem to break the downlevel mounts.
Tom.
next prev parent reply other threads:[~2019-05-30 17:12 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-30 0:41 [PATCH 0/9] Multiple network connections for a single NFS mount NeilBrown
2019-05-30 0:41 ` [PATCH 4/9] SUNRPC: enhance rpc_clnt_show_stats() to report on all xprts NeilBrown
2019-05-30 0:41 ` [PATCH 6/9] NFS: Add a mount option to specify number of TCP connections to use NeilBrown
2019-05-30 0:41 ` [PATCH 9/9] NFS: Allow multiple connections to a NFSv2 or NFSv3 server NeilBrown
2019-05-30 0:41 ` [PATCH 3/9] NFS: send state management on a single connection NeilBrown
2019-07-23 18:11 ` Schumaker, Anna
2019-07-23 22:54 ` NeilBrown
2019-07-31 2:05 ` [PATCH] NFS: add flags arg to nfs4_call_sync_sequence() NeilBrown
2019-05-30 0:41 ` [PATCH 2/9] SUNRPC: Allow creation of RPC clients with multiple connections NeilBrown
2019-05-30 0:41 ` [PATCH 1/9] SUNRPC: Add basic load balancing to the transport switch NeilBrown
2019-05-30 0:41 ` [PATCH 5/9] SUNRPC: add links for all client xprts to debugfs NeilBrown
2019-05-30 0:41 ` [PATCH 7/9] NFSv4: Allow multiple connections to NFSv4.x servers NeilBrown
2019-05-30 0:41 ` [PATCH 8/9] pNFS: Allow multiple connections to the DS NeilBrown
2019-05-30 17:05 ` Tom Talpey [this message]
2019-05-30 17:20 ` [PATCH 0/9] Multiple network connections for a single NFS mount Olga Kornievskaia
2019-05-30 17:41 ` Tom Talpey
2019-05-30 18:41 ` Olga Kornievskaia
2019-05-31 1:45 ` Tom Talpey
2019-05-30 22:38 ` NeilBrown
2019-05-31 1:48 ` Tom Talpey
2019-05-31 2:31 ` NeilBrown
2019-05-31 12:39 ` Tom Talpey
2019-05-30 23:53 ` Rick Macklem
2019-05-31 0:15 ` J. Bruce Fields
2019-05-31 1:01 ` NeilBrown
2019-05-31 2:20 ` Rick Macklem
2019-05-31 12:36 ` Tom Talpey
2019-05-31 13:33 ` Trond Myklebust
2019-05-30 17:56 ` Chuck Lever
2019-05-30 18:59 ` Olga Kornievskaia
2019-05-30 22:56 ` NeilBrown
2019-05-31 13:46 ` Chuck Lever
2019-05-31 15:38 ` J. Bruce Fields
2019-06-11 1:09 ` NeilBrown
2019-06-11 14:51 ` Chuck Lever
2019-06-11 15:05 ` Tom Talpey
2019-06-11 15:20 ` Trond Myklebust
2019-06-11 15:35 ` Chuck Lever
2019-06-11 16:41 ` Trond Myklebust
2019-06-11 17:32 ` Chuck Lever
2019-06-11 17:44 ` Trond Myklebust
2019-06-12 12:34 ` Steve Dickson
2019-06-12 12:47 ` Trond Myklebust
2019-06-12 13:10 ` Trond Myklebust
2019-06-11 15:34 ` Olga Kornievskaia
2019-06-11 17:46 ` Chuck Lever
2019-06-11 19:13 ` Olga Kornievskaia
2019-06-11 20:02 ` Tom Talpey
2019-06-11 20:09 ` Chuck Lever
2019-06-11 21:10 ` Olga Kornievskaia
2019-06-11 21:35 ` Tom Talpey
2019-06-11 22:55 ` NeilBrown
2019-06-12 12:55 ` Tom Talpey
2019-06-11 23:02 ` NeilBrown
2019-06-11 23:21 ` NeilBrown
2019-06-12 12:52 ` Tom Talpey
2019-06-11 23:42 ` NeilBrown
2019-06-12 12:39 ` Steve Dickson
2019-06-12 17:36 ` Chuck Lever
2019-06-12 23:03 ` NeilBrown
2019-06-13 16:13 ` Chuck Lever
2019-06-12 1:49 ` NeilBrown
2019-06-12 18:32 ` Chuck Lever
2019-06-12 23:37 ` NeilBrown
2019-06-13 16:27 ` Chuck Lever
2019-05-31 0:24 ` J. Bruce Fields
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