Jackie Tung
2016-Aug-08 20:47 UTC
[Gluster-users] gluster profile mode - showing unexpected WRITE fops
Hi, I?m doing some benchmarking vs our trial GlusterFS setup (distributed replicated, 20 bricks configured as 10 pairs). I?m running 3.6.9 currently. Our benchmarking load involves a large number of concurrent readers that continuously pick random file / offsets to read. No writes are ever issued. However I?m seeing the following gluster profiling output: Block Size: 32768b+ 65536b+ 131072b+ No. of Reads: 0 0 6217035 No. of Writes: 87967 25443 4372800 Why are there writes at all? Are seeks being shown here as writes? Thanks, Jackie -- The information in this email is confidential and may be legally privileged. It is intended solely for the addressee. Access to this email by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful.
Shyam
2016-Aug-10 18:23 UTC
[Gluster-users] gluster profile mode - showing unexpected WRITE fops
Hi, How was the profile data collected? Was it a cumulative profile output or an incremental profile output? How did the initial data get written to the 20 bricks, before the read workload was started? What I suspect here is that, you are collecting cumulative output, which is possibly showing up the initial writes that were performed to populate the volume. From the code I do not see seek tracked in iostats, so it is not the *seek* that is bloating these numbers up. Regards, Shyam On 08/08/2016 04:47 PM, Jackie Tung wrote:> Hi, > > I?m doing some benchmarking vs our trial GlusterFS setup (distributed replicated, 20 bricks configured as 10 pairs). I?m running 3.6.9 currently. Our benchmarking load involves a large number of concurrent readers that continuously pick random file / offsets to read. No writes are ever issued. However I?m seeing the following gluster profiling output: > > Block Size: 32768b+ 65536b+ 131072b+ > No. of Reads: 0 0 6217035 > No. of Writes: 87967 25443 4372800 > > Why are there writes at all? Are seeks being shown here as writes? > > Thanks, > Jackie >