Thanks for the reply Eric. Please see my responses inline: On Tue, Aug 25, 2015 at 2:44 PM, Eric Sandeen <sandeen@xxxxxxxxxxx> wrote: > On 8/25/15 3:32 PM, Shrinand Javadekar 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. > > How did you do the above twice, out of curiosity? If it's the same set of disks, > the 3rd mkfs would require "-f" to overwrite the old format. I did this on 2 different setups. Formatted the new disks with mkfs.xfs. Ran the workload. Reformatted the disks with mkfs.xfs -f. Ran the workload. > >> Any ideas why this might be happening? > > With the paucity of information you've provided, nope! Apologies. What more information can I provide? > > What version of xfsprogs are you using? # xfs_repair -V xfs_repair version 3.1.9 > What was the output of mkfs.xfs each time; did the geometry differ? I have the output of xfs_info /mount/point from the first experiment and that of mkfs.xfs -f. One difference I see is that reformatting adds projid32bit=0 for the inode section. > > -f sets force_overwrite, which only does 3 things: > > 1) overwrite existing filesystem signatures > 3) zeros out old xfs structures on disk > 2) allow mkfs to proceed on a misaligned device > > I don't see why any of those behaviors would change runtime behavior. > > Maybe you have other variables in your performance testing, and two > tests isn't enough to sort out noise? We have seen this again on a third setup of one of my colleagues. What more data can I look at for identifying the differences? > > -Eric > >> Thanks in advance. >> -Shri >> >> _______________________________________________ >> xfs mailing list >> xfs@xxxxxxxxxxx >> http://oss.sgi.com/mailman/listinfo/xfs >> > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
