Right now, the AthlonXP machine is booted into Linux, and I'm getting same raw speed as when it is in Solaris, from PCI Sil3114 with Seagate 320G ( 7200.10):
dd if=/dev/sdb of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out 1310720000 bytes (1.3 GB) copied, 16.7756 seconds, 78.1 MB/s sudo dd if=./test.mov of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out 1310720000 bytes (1.3 GB) copied, 24.2731 seconds, 54.0 MB/s <-- some overhead compared to raw speed of same disk above same machine, onboard ATA, Seagate 120G: dd if=/dev/hda of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out 1310720000 bytes (1.3 GB) copied, 22.5892 seconds, 58.0 MB/s On another machine with Pentium D 3.0GHz and ICH7 onboard SATA in AHCI mode, running Darwin OS: from a Seagate 500G (7200.10): dd if=/dev/rdisk0 of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out 1310720000 bytes transferred in 17.697512 secs (74062388 bytes/sec) same disk, access through file system (HFS+) dd if=./Summer\ 2006\ with\ Cohen\ 4 of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out 1310720000 bytes transferred in 20.381901 secs (64308035 bytes/sec) <- very small overhead compared to raw access above! same Intel machine, Seagate 200G (7200.8, I think): dd if=/dev/rdisk1 of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out 1310720000 bytes transferred in 20.850229 secs (62863578 bytes/sec) Modern disk drives are definitely fast and pushing close to 80MB/s raw performance. And some file systems can get over 85% of that with simple sequential access. So far, on these particular hardware and software combinations, I have, filesystem performance as percentage of raw disk performance for sequential unchached read: HFS+: 86% ext3 and UFS: 70% ZFS: 45% On 5/14/07, Richard Elling <[EMAIL PROTECTED]> wrote:
Marko Milisavljevic wrote: > I missed an important conclusion from j's data, and that is that single > disk raw access gives him 56MB/s, and RAID 0 array gives him > 961/46=21MB/s per disk, which comes in at 38% of potential performance. > That is in the ballpark of getting 45% of potential performance, as I am > seeing with my puny setup of single or dual drives. Of course, I don't > expect a complex file system to match raw disk dd performance, but it > doesn't compare favourably to common file systems like UFS or ext3, so > the question remains, is ZFS overhead normally this big? That would mean > that one needs to have at least 4-5 way stripe to generate enough data > to saturate gigabit ethernet, compared to 2-3 way stripe on a "lesser" > filesystem, a possibly important consideration in SOHO situation. Could you post iostat data for these runs? Also, as I suggested previously, try with checksum off. AthlonXP doesn't have a reputation as a speed deamon. BTW, for 7,200 rpm drives, which are typical in desktops, 56 MBytes/s isn't bad. The media speed will range from perhaps [30-40]-[60-75] MBytes/s judging from a quick scan of disk vendor datasheets. In other words, it would not surprise me to see 4-5 way stripe being required to keep a GbE saturated. -- richard
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