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Re: [Qemu-devel] migration question: disk images on nfs server
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] migration question: disk images on nfs server |
Date: |
Fri, 07 Feb 2014 13:26:57 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 |
Il 07/02/2014 10:41, Marcin Gibuła ha scritto:
>> For NFS you need to use the sync mount option to force the NFS client to
>> sync to
>> server on writes.
>
> Isn't opening with O_DIRECT enough? (for linux nfs client at least)
Yeah, the man page says:
If neither sync nor async is specified (or
if the async option is specified), the NFS client delays sending appli‐
cation writes to the server until any of these events occur:
Memory pressure forces reclamation of system memory resources.
An application flushes file data explicitly with sync(2),
msync(2), or fsync(3).
An application closes a file with close(2).
The file is locked/unlocked via fcntl(2).
In other words, under normal circumstances, data written by an applica‐
tion may not immediately appear on the server that hosts the file.
QEMU does flush file data with fsync(3). It's not the first time I hear about
needing the sync option though.
Paolo
- [Qemu-devel] migration question: disk images on nfs server, Alexey Kardashevskiy, 2014/02/06
- Re: [Qemu-devel] migration question: disk images on nfs server, Orit Wasserman, 2014/02/07
- Re: [Qemu-devel] migration question: disk images on nfs server, Marcin Gibuła, 2014/02/07
- Re: [Qemu-devel] migration question: disk images on nfs server,
Paolo Bonzini <=
- Re: [Qemu-devel] migration question: disk images on nfs server, Alexey Kardashevskiy, 2014/02/07
- Re: [Qemu-devel] migration question: disk images on nfs server, Orit Wasserman, 2014/02/07
- Re: [Qemu-devel] migration question: disk images on nfs server, Marcin Gibuła, 2014/02/07
- Re: [Qemu-devel] migration question: disk images on nfs server, Orit Wasserman, 2014/02/07
- Re: [Qemu-devel] migration question: disk images on nfs server, Marcin Gibuła, 2014/02/07
- Re: [Qemu-devel] migration question: disk images on nfs server, Orit Wasserman, 2014/02/07
- Re: [Qemu-devel] migration question: disk images on nfs server, Kevin Wolf, 2014/02/08