I'm guessing that all of these issues have to do with the inherent asynchronous nature of sysfs. The time between an event happening and the sysfs data representing it is not zero, and when the system becomes busy this time delta can be large enough so that assumptions in the code start breaking down.
As long as we rely so heavily on sysfs we will continue to have problems, especially on highly-loaded system, or systems with huge numbers of targets/LUNs. Even better caching will not help in this case. The only thing that might mitigate this issue IMHO, again assuming we continue to use sysfs, is to build in reasonable retries in every sysfs access. Chris, is your research on large number of targets lead you to believe there is a better approach? On Tuesday, June 21, 2016 at 3:20:12 PM UTC-7, Anand Subramanian wrote: > > Hi All, > > We have a large number of iscsi logins and logouts in our setup. During > the logouts we see the following messages. Eventually the logouts succeed > after retries but does this point to some more fundamental mismatch which > should be corrected or can these be ignored? > > 2016-06-19 13:55:12 INFO miutils.py:2255 Executed: sudo iscsiadm --m node > --logout --target > iqn.2010-06.com.xyz:7b1652d2-4185-4b01-97cd-8add64a97c37-tgt0 > > 2016-06-19 13:55:12 INFO minutils.py:2259 stderr: iscsiadm: Could not > lookup devpath for session174. Possible sysfs incompatibility. > > > *iscsiadm: Could not lookup devpath for session176. Possible sysfs > incompatibility.* > > > We are using open-iscsi-2.0-872-rc4-bnx2i on CentOS with Linux version > 3.10.0-229.26.2.el6 > > > Based on past ML posts, I have checked "whereis iscsid" and iscsiadm and > they all seem to be of the same bitness (x86_64). > > > We do a fairly large number of logins and logouts and one of the things to > try out for improving performance would be Chris' patches from another > recent thread. Will give it a shot based on our open-iscsi versions for the > patch and see how that goes. > > > But the above messages during logouts are seen as well as some other > messages during logins > > > 2016-06-19 13:56:18 INFO minutils.py:2255 Executed: sudo iscsiadm --m node > --targetname=iqn.2010-06.com.xyz:de49c23b-76c2-422d-8659-74ad8a47e864-tgt3 > --login --portal 10.4.81.16 > > 2016-06-19 13:56:18 INFO minutils.py:2259 stderr: *iscsiadm: could not > read session targetname: 5* > > iscsiadm: could not find session info for session17 > > > TIA for any pointers/inputs. > > > Regards, > > Anand > -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to open-iscsi+unsubscr...@googlegroups.com. To post to this group, send email to open-iscsi@googlegroups.com. Visit this group at https://groups.google.com/group/open-iscsi. For more options, visit https://groups.google.com/d/optout.
