Hello all, I tried a simple test: 1. Installed an iSCSI target. I tried this with both IET (iscsitarget.sourceforge.net) and tgt (apt-get install tgt). 2. Created a 2GB file to use as the target. 3. Connected to the target with iscsiadm. 4. Ran the following command to test read throughput: dd if=/dev/sdc of=/dev/null bs=128M count=16 5. Ran the following command to test write throughput: dd if=/dev/zero of=/dev/sdc bs=128M count=16 (where /dev/sdc is the iSCSI device)
For read throughput I get about 98MB/s, and for write throughput about 75MB/s. I tried to figure out why writes are so much slower, so I opened up wireshark and looked at the packets. I captured 256,270 packets. Here are some statistics from wireshark: Bad checksum(TCP): 35,963 Bad checksum(UDP): 4 Previous segment lost (TCP): 24,502 ACKed lost segment (TCP): 51,651 I would bet that this has something to do with the low throughput. (For the read test, everything looks fine in wireshark). I uploaded the compressed dump here: http://www.fsl.cs.sunysb.edu/~avishay/iscsi-loopback-write.dump.tgz I'm assuming the problem lies in open-iscsi because I tried two different targets with the same results, and I'm working over loopback (no network issues). Some more info: # uname -a Linux guri 2.6.24-16-server #1 SMP Thu Apr 10 13:15:38 UTC 2008 x86_64 GNU/Linux # cat /etc/issue Ubuntu 8.04.1 \n \l # iscsiadm -V iscsiadm version 2.0-865 # dpkg -l | grep open-iscsi ii open-iscsi 2.0.865-1ubuntu3 High performance, transport independent iSCS # iscsiadm -m discovery -t st -p 127.0.0.1 127.0.0.1:3260,1 iqn.2001-04.com.example:storage.disk2.sys1.xyz # iscsiadm -m node -T iqn.2001-04.com.example:storage.disk2.sys1.xyz - p 127.0.0.1 -l Login session [iface: default, target: iqn. 2001-04.com.example:storage.disk2.sys1.xyz, portal: 127.0.0.1,3260] # fdisk -l /dev/sdc Disk /dev/sdc: 2147 MB, 2147483648 bytes 67 heads, 62 sectors/track, 1009 cylinders Units = cylinders of 4154 * 512 = 2126848 bytes Disk identifier: 0x00000000 Disk /dev/sdc doesn't contain a valid partition table Any help would be appreciated! Thanks a lot! Avishay --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "open-iscsi" group. To post to this group, send email to open-iscsi@googlegroups.com To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/open-iscsi -~----------~----~----~----~------~----~------~--~---
