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
gershwin:[~] > ping -A -s 8192 192.168.0.2
PING 192.168.0.2 (192.168.0.2) 8192(8220) bytes of data.
8200 bytes from 192.168.0.2: icmp_seq=1 ttl=64 time=0.693 ms
8200 bytes from 192.168.0.2: icmp_seq=2 ttl=64 time=0.595 ms
8200 bytes from 192.168.0.2: icmp_seq=3 ttl=64 time=0.583 ms
8200 bytes from 192.168.0.2: icmp_seq=4 ttl=64 time=0.589 ms
8200 bytes from 192.168.0.2: icmp_seq=5 ttl=64 time=0.580 ms
8200 bytes from 192.168.0.2: icmp_seq=6 ttl=64 time=0.594 ms
8200 bytes from 192.168.0.2: icmp_seq=7 ttl=64 time=0.580 ms
8200 bytes from 192.168.0.2: icmp_seq=8 ttl=64 time=0.592 ms
8200 bytes from 192.168.0.2: icmp_seq=9 ttl=64 time=0.589 ms
8200 bytes from 192.168.0.2: icmp_seq=10 ttl=64 time=0.571 ms
8200 bytes from 192.168.0.2: icmp_seq=11 ttl=64 time=0.588 ms
8200 bytes from 192.168.0.2: icmp_seq=12 ttl=64 time=0.580 ms
8200 bytes from 192.168.0.2: icmp_seq=13 ttl=64 time=0.587 ms
--- 192.168.0.2 ping statistics ---
13 packets transmitted, 13 received, 0% packet loss, time 2400ms
rtt min/avg/max/mdev = 0.571/0.593/0.693/0.044 ms, ipg/ewma 200.022/0.607 ms
gershwin:[~] >
Both initiator and target are alone on a gigabit NIC (Tigon3). On
target server, istd1 takes 100% of a CPU (and only one CPU, even my
T1000 can simultaneous run 32 threads). I think the limitation comes
from istd1.
You want your avg ping time for 8192 byte payloads to be 300us or less.
1000/.268 = 3731 IOPS @ 8k = 30 MB/s
If you use apps that do overlapping asynchronous IO you can see better
numbers.
Regards,
JKB
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