From: "Marcin Gibuła" <m.gibula@beyond.pl>
To: Orit Wasserman <owasserm@redhat.com>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] migration question: disk images on nfs server
Date: Fri, 07 Feb 2014 13:54:16 +0100 [thread overview]
Message-ID: <52F4D778.6070001@beyond.pl> (raw)
In-Reply-To: <52F4D5C6.1050206@redhat.com>
> It is more a NFS issue, if you have a file in NFS that two users in
> two different host are accessing (one at least write to it) you will
> need to enforce the "sync" option.
> Even if you flush all the data and close the file the NFS client can still
> have cached data that it didn't sync to the server.
Do you know if is applies to linux O_DIRECT writes as well?
From comment in fs/nfs/direct.c:
* When an application requests uncached I/O, all read and write requests
* are made directly to the server; data stored or fetched via these
* requests is not cached in the Linux page cache. The client does not
* correct unaligned requests from applications. All requested bytes are
* held on permanent storage before a direct write system call returns to
* an application.
--
mg
next prev parent reply other threads:[~2014-02-07 12:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-07 4:35 [Qemu-devel] migration question: disk images on nfs server Alexey Kardashevskiy
2014-02-07 7:46 ` Orit Wasserman
2014-02-07 9:41 ` Marcin Gibuła
2014-02-07 12:26 ` Paolo Bonzini
2014-02-07 12:10 ` Alexey Kardashevskiy
2014-02-07 12:47 ` Orit Wasserman
2014-02-07 12:54 ` Marcin Gibuła [this message]
2014-02-07 13:36 ` Orit Wasserman
2014-02-07 13:44 ` Marcin Gibuła
2014-02-07 13:57 ` Orit Wasserman
2014-02-08 8:30 ` Kevin Wolf
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