Hi, my apologies if this was asked and answered before, but I just tried to get a HOWTO on iSCSI and multipath, but failed to find something really usable.
I have a question regarding various timeouts, specifically (SCSI command, TCP connection, multipath). Somehow those timeout s are hierarchical, meaning the multipath daemon (or kernel module) will send some command to a virtual SCSI device (iSCSI here), then the iSCSI layer will send a TCP packet on the wire, and after some further unpacking a more or less real SCSI device will receive a command. If I name those timeouts tm (multipath), tt (TCP), and ts (SCSI) respectively, should the following be true: tm < tt < ts Or should the exact opposite be true: tm > tt > ts The problem is that the "connection" the multipath daemon sees is actually a multi-hop and multi-protocol connection. So multipath should probably try a different iSCSI/TCP connection if the network (TCP) fails to respond. Unfortunately iSCSI will also try some kind of connection recovery, but that might be slower. Finally the connection could be fine, but the SCSI target could be unable to respond in time (e.g. persistent disk read error). AFAIK, it's not a problem if the same iSCSI command arrives via different patch at the iSCSI target (not saying: SCSI device), so maybe if multipath is trying a different patch while iSCSI is still trying TCP connection recovery could be OK. Can anybody put some light into this (or point me to some existing docs)? Regards, Ulrich --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "open-iscsi" group. To post to this group, send email to firstname.lastname@example.org 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 -~----------~----~----~----~------~----~------~--~---