Re: CephFS "move" operation

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Am 25.05.2018 um 14:50 schrieb John Spray:
> On Fri, May 25, 2018 at 1:10 PM, Oliver Freyermuth
> <freyermuth@xxxxxxxxxxxxxxxxxx> wrote:
>> Dear Cephalopodians,
>>
>> I was wondering why a simple "mv" is taking extraordinarily long on CephFS and must note that,
>> at least with the fuse-client (12.2.5) and when moving a file from one directory to another,
>> the file appears to be copied first (byte by byte, traffic going through the client?) before the initial file is deleted.
>>
>> Is this true, or am I missing something?
> 
> A mv should not involve copying a file through the client -- it's
> implemented in the MDS as a rename from one location to another.
> What's the observation that's making it seem like the data is going
> through the client?

The fact that it's happening with only about 1 GBit/s and all OSDs are reading and writing. 
I will also check the network interface of the client next time it occurs. Also, ceph-fuse was taking 50 % CPU load just from this. 

Also, I observe the file at the source being kept during the copy,
and the file at the target growing slowly. So it's definitely a copy, and only at the end the source file is deleted. 

> 
> John
> 
>>
>> For large files, this might be rather time consuming,
>> and we should certainly advise all our users to not move files around needlessly if this is the case.
>>
>> Cheers,
>>         Oliver
>>
>>
>> _______________________________________________
>> ceph-users mailing list
>> ceph-users@xxxxxxxxxxxxxx
>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>

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