[lustre-discuss] OST partition sizes

Alexander I Kulyavtsev aik at fnal.gov
Wed Apr 29 09:38:17 PDT 2015

ior/bin/IOR.mpiio.mvapich2-2.0b -h

 -t N  transferSize -- size of transfer in bytes (e.g.: 8, 4k, 2m, 1g)

IOR reports it in the log :

Command line used: /home/aik/lustre/benchmark/git/ior/bin/IOR.mpiio.mvapich2-2.0b -v -a MPIIO -i5 -g -e -w -r -b 16g -C -t 8k -o /mnt/lfs/admin/iotest/ior/stripe_2/ior-testfile.ssf

        api                = MPIIO (version=3, subversion=0)
        test filename      = /mnt/lfs/admin/iotest/ior/stripe_2/ior-testfile.ssf
        access             = single-shared-file, independent
        pattern            = segmented (1 segment)
        ordering in a file = sequential offsets
        ordering inter file=constant task offsets = 1
        clients            = 32 (8 per node)
        repetitions        = 5
        xfersize           = 8192 bytes
        blocksize          = 16 GiB
        aggregate filesize = 512 GiB

Here we have xfersize 8k, each client of 32 writes 16GB, so the aggregate file size is 512GB.

I would expect records size to be ~1MB for our workloads.

Best regards, Alex.

On Apr 29, 2015, at 11:07 AM, Scott Nolin <scott.nolin at ssec.wisc.edu<mailto:scott.nolin at ssec.wisc.edu>> wrote:

Ok I looked up my notes.

I'm not really sure what you mean by record size. I assumed when I do a file per process the block size = file size. And that's what I see dropped on the filesystem.

I did -F -b <size>

With block sizes 1MB, 20MB, 100MB, 200MB, 500MB

2, 4, 8, 16 threads on 1 to 4 clients.

I assumed 2 threads on 1 client looks a lot like a client writing or reading 2 files. I didn't bother looking at 1 thread.

Later I just started doing 100MB tests since it's a very common file size for us. Plus I didn't see real big difference once size gets bigger than that.


On 4/29/2015 10:24 AM, Alexander I Kulyavtsev wrote:
What range of record sizes did you use for IOR? This is more important
than file size.
100MB is small, overall data size (# of files) shall be twice as memory.
I ran series of test for small record size for raidz2 10+2; will re-run
some tests after upgrading to .

Single file performance differs substantially from file per process.


On Apr 29, 2015, at 9:38 AM, Scott Nolin <scott.nolin at ssec.wisc.edu<mailto:scott.nolin at ssec.wisc.edu>
<mailto:scott.nolin at ssec.wisc.edu>> wrote:

I used IOR, singlefile, 100MB files. That's the most important
workload for us. I tried several different file sizes, but 100MB
seemed a reasonable compromise for what I see the most. We rarely or
never do file striping.

I remember I did see a difference between 10+2 and 8+2. Especially at
smaller numbers of clients and threads, the 8+2 performance numbers
were more consistent, made a smoother curve. 10+2 with not a lot of
threads the performance was more variable.

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