To give you fine people an update, it seems that the reason for the skewed results shown earlier is due to Veritas' ability to take advantage of all the free memory available on my server. My test system has 32G of Ram, and my test data file is 10G. Basically, Veritas was able to cache the entire data file.
On the suggestion that I use a larger data file, I have increased the file to 100G and have re-run my Veritas tests with an 8k File Block and 8k Request Block size. In doing this, I have run into a different issue, which I have now resolved. That being - my server became fully unresponsive during testing! Basically, Veritas allowed itself to consume all the memory of my server, all 32G, and then when it had used all of its memory, it looked for more and hung the server due to resource contention. To alleviate this problem, I tuned the Veritas file system using the write_throttle tunable. I first set this to be 99.5% of my Ram, then 50% and now I am running at about 256Mb (32651 pages). The reason I had decreased the values down to the current (32651) page size is that, while the server would be responsive, my test volume would not be so. It took 35 minutes for the paging to stop when I had set the write_throttle to 50% of Ram, and only after that paging completed did the test resume. At the current value, the test will continue for a period, then flush, continue, etc. Given my current configuration, I now see an IO rate of 756 versus my prior 27,329!!! I am continuing my testing, and will re-test UFS and ZFS with the larger file size as well to properly discover the differences. Also, in subsequent testing, I will also test with a full un-buffered Veritas & UFS volume to compare with ZFS, which may be a more reasonable test due to ZFS's copy-on-write architecture. I will send out the full results when they are compiled. This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
