On Thu, 2007-10-18 at 17:03 -0400, Ross S. W. Walker wrote: > BERTRAND Joël wrote: > > > > BERTRAND Joël wrote: > > > I can format serveral times (mkfs.ext3) a 1.5 TB volume > > over iSCSI > > > without any trouble. I can read and write on this virtual > > disk without > > > any trouble. > > > > > > Now, I have configured ietd with : > > > > > > Lun 0 Sectors=1464725758,Type=nullio > > > > > > and I run on initiator side : > > > > > > Root gershwin:[/dev] > dd if=/dev/zero of=/dev/sdj bs=8192 > > > 479482+0 records in > > > 479482+0 records out > > > 3927916544 bytes (3.9 GB) copied, 153.222 seconds, 25.6 MB/s > > > > > > Root gershwin:[/dev] > dd if=/dev/zero of=/dev/sdj bs=8192 > > > > > > I'm waitinfor a crash. No one when I write these lines. > > I suspect > > > an interaction between raid and iscsi. > > > > I simultanely run : > > > > Root gershwin:[/dev] > dd if=/dev/zero of=/dev/sdj bs=8192 > > 8397210+0 records in > > 8397210+0 records out > > 68789944320 bytes (69 GB) copied, 2732.55 seconds, 25.2 MB/s > > > > and > > > > Root gershwin:[~] > dd if=/dev/sdj of=/dev/null bs=8192 > > 739200+0 records in > > 739199+0 records out > > 6055518208 bytes (6.1 GB) copied, 447.178 seconds, 13.5 MB/s > > > > without any trouble. > > The speed can definitely be improved. Look at your network setup > and use ping to try and get the network latency to a minimum. > > # ping -A -s 8192 172.16.24.140 > .... > --- 172.16.24.140 ping statistics --- > 14058 packets transmitted, 14057 received, 0% packet loss, time 9988ms > rtt min/avg/max/mdev = 0.234/0.268/2.084/0.041 ms, ipg/ewma 0.710/0.260 ms > > You want your avg ping time for 8192 byte payloads to be 300us or less. > > 1000/.268 = 3731 IOPS @ 8k = 30 MB/s he use normal dd, which in turn use page cache and read ahead, so actual request size at scsi layer can be much larger than 8k.... > > If you use apps that do overlapping asynchronous IO you can see better > numbers. > > -Ross > > ______________________________________________________________________ > This e-mail, and any attachments thereto, is intended only for use by > the addressee(s) named herein and may contain legally privileged > and/or confidential information. If you are not the intended recipient > of this e-mail, you are hereby notified that any dissemination, > distribution or copying of this e-mail, and any attachments thereto, > is strictly prohibited. If you have received this e-mail in error, > please immediately notify the sender and permanently delete the > original and any copy or printout thereof. > -- Ming Zhang @#$%^ purging memory... (*!% http://blackmagic02881.wordpress.com/ http://www.linkedin.com/in/blackmagic02881 -------------------------------------------- - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
