Harley: > I had tried other sizes with much the same results, but > hadnt gone as large as 128K. With bs=128K, it gets worse: > > | # time dd if=zeros-10g of=/dev/null bs=128k count=102400 > | 81920+0 records in > | 81920+0 records out > | > | real 2m19.023s > | user 0m0.105s > | sys 0m8.514s
I may have done my math wrong, but if we assume that the real time is the actual amount of time we spent performing the I/O (which may be incorrect) haven't you done better here? In this case you pushed 81920 128k records in ~139 seconds -- approx 75437 k/sec. Using ZFS with 8k bs, you pushed 102400 8k records in ~68 seconds -- approx 12047 k/sec. Using the raw device you pushed 102400 8k records in ~23 seconds -- approx 35617 k/sec. I may have missed something here, but isn't this newest number the highest performance so far? What does iostat(1M) say about your disk read performance? > Is there any other info I can provide which would help? Are you just trying to measure ZFS's read performance here? It might be interesting to change your outfile (of) argument and see if we're actually running into some other performance problem. If you change of=/tmp/zeros does performance improve or degrade? Likewise, if you write the file out to another disk (UFS, ZFS, whatever), does this improve performance? -j _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
