[Bug 305853] Re: open-iscsi slow disk performance

[Aaron Thul]

I have been doing some experimenting and I found something I do not
understand and it may have something to do with this problem.  I
recently took node that when the iscsi disks are running slow I am
missing a process, specifically: /usr/sbin/iscsid.

It starts out that iscsi is running slow, I take a look and see what iscsi is doing...
root at mara:~# ps -ef | grep scsi
root      1493     2  0  2008 ?        00:00:00 [scsi_eh_0]
root      2433     2  0  2008 ?        00:00:00 [scsi_eh_1]
root      2434     2  0  2008 ?        00:00:00 [scsi_eh_2]
root      5138     2  0  2008 ?        00:00:00 [scsi_eh_3]
root      5139     2  0  2008 ?        00:23:42 [scsi_wq_3]
root     26621 26468  0 12:13 pts/0    00:00:00 grep scsi
root     27919     1  0 Jan05 ?        00:00:00 /sbin/iscsid


I do my usually parlor trick to get it running at proper speed again:
root at mara:~# dpkg -i /home/apthul/open-iscsi_2.0.730-1_amd64.deb ; aptitude install open-iscsi
dpkg - warning: downgrading open-iscsi from 2.0.865-1ubuntu3 to 2.0.730-1.
(Reading database ... 27321 files and directories currently installed.)
Preparing to replace open-iscsi 2.0.865-1ubuntu3 (using .../open-iscsi_2.0.730-1_amd64.deb) ...
 * Disconnecting iSCSI targets
   ...done.
 * Stopping iSCSI initiator service
   ...done.
Unpacking replacement open-iscsi ...
Setting up open-iscsi (2.0.730-1) ...
Installing new version of config file /etc/init.d/open-iscsi ...
 * Starting iSCSI initiator service iscsid
   ...done.
 * Setting up iSCSI targets
   ...done.

Preparing to replace open-iscsi 2.0.730-1 (using .../open-iscsi_2.0.865-1ubuntu3_amd64.deb) ...
 * Disconnecting iSCSI targets
   ...done.
 * Stopping iSCSI initiator service
   ...done.
Unpacking replacement open-iscsi ...
Setting up open-iscsi (2.0.865-1ubuntu3) ...
Installing new version of config file /etc/init.d/open-iscsi ...
update-rc.d: /etc/init.d/remove: file does not exist
 * Starting iSCSI initiator service iscsid
   ...done.
 * Setting up iSCSI targets


Everything test out well and I decide I wanted to see what was running now:
apthul at mara:~$ ps -ef | grep scsi
root      1493     2  0  2008 ?        00:00:00 [scsi_eh_0]
root      2433     2  0  2008 ?        00:00:00 [scsi_eh_1]
root      2434     2  0  2008 ?        00:00:00 [scsi_eh_2]
root      5138     2  0  2008 ?        00:00:00 [scsi_eh_3]
root      5139     2  0  2008 ?        00:23:42 [scsi_wq_3]
root     26742     1  0 12:13 ?        00:00:00 /usr/sbin/iscsid                   ##What the heck is that!???
root     26960     1  0 12:13 ?        00:00:00 /sbin/iscsid
root     26961     1  0 12:13 ?        00:00:00 /sbin/iscsid
apthul   27018 22441  0 12:16 pts/0    00:00:00 grep scsi
apthul at mara:~$ iostat -cdmtx 10 999999

I decided to go see what it was:
apthul at mara:~$  ls -latr /usr/sbin/iscsid
ls: cannot access /usr/sbin/iscsid: No such file or directory


It is not there but /usr/sbin/iscsid is still running, it must have been deleted from the open-scsi upgrade.  Could this be the magic that is keeping my open-iscsi running at proper speeds?  Could it be that /usr/sbin/iscsid running is causing libraries to not be reloaded that are keeping the open-iscsi running properly?

-- 
open-iscsi slow disk performance
https://bugs.launchpad.net/bugs/305853
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