Specifically related to BTRFS, if you have random IO to existing objects
it will cause terrible fragmentation due to COW. BTRFS is often faster
than XFS initially but after it starts fragmenting can become much
slower for sequential reads. You may want to try XFS again and see if
you can improve the read performance (increasing read ahead both on the
cephfs client and on the underlying OSD block devices to something like
4MB might help).
Mark
On 03/27/2015 11:47 AM, Barclay Jameson wrote:
Opps I should have said that I am not just writing the data but copying it :
time cp Small1/* Small2/*
Thanks,
BJ
On Fri, Mar 27, 2015 at 11:40 AM, Barclay Jameson
<almightybeeij@xxxxxxxxx> wrote:
I did a Ceph cluster install 2 weeks ago where I was getting great
performance (~= PanFS) where I could write 100,000 1MB files in 61
Mins (Took PanFS 59 Mins). I thought I could increase the performance
by adding a better MDS server so I redid the entire build.
Now it takes 4 times as long to write the same data as it did before.
The only thing that changed was the MDS server. (I even tried moving
the MDS back on the old slower node and the performance was the same.)
The first install was on CentOS 7. I tried going down to CentOS 6.6
and it's the same results.
I use the same scripts to install the OSDs (which I created because I
can never get ceph-deploy to behave correctly. Although, I did use
ceph-deploy to create the MDS and MON and initial cluster creation.)
I use btrfs on the OSDS as I can get 734 MB/s write and 1100 MB/s read
with rados bench -p cephfs_data 500 write --no-cleanup && rados bench
-p cephfs_data 500 seq (xfs was 734 MB/s write but only 200 MB/s read)
Could anybody think of a reason as to why I am now getting a huge regression.
Hardware Setup:
[OSDs]
64 GB 2133 MHz
Dual Proc E5-2630 v3 @ 2.40GHz (16 Cores)
40Gb Mellanox NIC
[MDS/MON new]
128 GB 2133 MHz
Dual Proc E5-2650 v3 @ 2.30GHz (20 Cores)
40Gb Mellanox NIC
[MDS/MON old]
32 GB 800 MHz
Dual Proc E5472 @ 3.00GHz (8 Cores)
10Gb Intel NIC
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