we are using an emc vplex metro cluster with 2 emc vmax 40k underneath.
looking at a DB2 workload (Data Warehouse usage) on AIX. DBMS seems to be writing to database files with a single writer thread per DB filesystem (16k write-size, random, direct-io).
The filesystems are JFS2 and have been created on vplex Distributed volumes (sync mirror, write through).
The write rate is about 10 Mbyte/s.
With a synthetic benchmark (fio, see config below) we can duplicate the scenario, yielding the same write rate.
Of course the write rate can be increased by using larger blocks, using more writer threads or even dropping direct-io in favour of cached io.
DBA guys are investigating whether they can tune this in the DBMS config. SAN switch parameters also are in discussion.
I'd appreciate if anyone would run below specified benchmark on a mirrored storage (be it host-based or storage-based) and offer their results for comparison.
thanks in advance
here is the fio config file I use, fio is a publicly available OSS io generator written by Jens Axboe, should be able to find it in your OSS repository for linux, aix, etc. (www.perzl.org/aix/ for example)
you run the above mentioned workload with fio --section=dbwriter1 <filename_of_file_as_mentioned_below>
it will produce IO for 6 minutes in directory as specified by "directory" on a file with "size" size (50g in my example, the amount should be free in the filesystem).
[global] invalidate=0 # invalidate cache not needed for dio fallocate=0 time_based=1 # run for specified amount of time direct=1 # directio ramp_time=5 # short delay before measuring runtime=360 # 6min [dbwriter1] description=dbwriter directory=/db2/XXX/sapdata1 size=50g # size of the file being created for the benchmark bs=16k # block size rw=randwrite ioengine=posixaio iodepth=32 # how much async ios to keep in-flight numjobs=1 # 1 thread