Does previously existing data on disk affect fragmentation?
On Tue, Aug 25, 2015 at 1:32 PM, Shrinand Javadekar
<shrinand@xxxxxxxxxxxxxx> wrote:
> Hi,
>
> I have 23 disks formatted with XFS on a single server. The workload is
> Openstack Swift. See this email from a few months ago about the
> details:
>
> http://oss.sgi.com/archives/xfs/2015-06/msg00108.html
>
> I am observing some strange behavior and would like to get some
> feedback about why this is happening.
>
> I formatted the disks with xfs (mkfs.xfs) and deployed Openstack Swift
> on it. Writing 100GB of data into Swift in batches of 20GB each gave
> us the following throughput:
>
> 20 GB: 93MB/s
> 40 GB: 65MB/s
> 60 GB: 52MB/s
> 80 GB: 50MB/s
> 100 GB: 48MB/s
>
> I then re-formatted the disks with mkfs.xfs -f and ran the experiment
> again. This time I got the following throughput:
>
> 20 GB: 118MB/s
> 40 GB: 95MB/s
> 60 GB: 74MB/s
> 80 GB: 68MB/s
> 100 GB: 63MB/s
>
> I've seen similar results twice.
>
> Any ideas why this might be happening?
>
> Thanks in advance.
> -Shri
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