I have a question concerning the expected behavior of dm_multipath connected to an EMC Clariion array. Different versions of multipath give different results when I disconnect all pathes to the storage. I have one server (SuSE SLES10 SP2, 2.6.16.60-0.3, multipath-tools 0.4.7-34.43) and another one (SLES 11, 2.6.27.19-5-default, 0.4.8- 40.1). Both versions recognize the Clariion without further setting in multipath.conf. The settings for the Clariion in multipath -t seem to be the same (especially queue_if_no_path + no_path_retry 60) Trying to setup a software mirror on top, i.e. trying to mirror the data into a second box, I observed the follwoing diffenrent behavior between these two versions: - on the SLES10 machine, disconnecting the disk in one Clariion results in IO error, the mirror breaks up, and the use IO continues on the surviving part of the mirror. This is the behavior which I want, and which I expected, and this was my understanding of "no_path_retry" - retry some times, then terminate IO. - on the SLES11 machine, the same attempt makes IO hang infinitely. The messages display that all pathes fail, and then "Entering recovery mode: max_retries=60" - but then, nothing happens; IOs hang. I tried to modify no_path_retry=1 in multipath.conf, and according to multipath -t, this setting is accepted - but again, the messages say "Retry=60"; i.e. this setting seems to be hardcoded into dm_emc. It is, however, possible to set "features 0" in multipath.conf; now it seems to work as desired - i.e. with this setting, IO doesnt hang, but is terminated with an IO error when I disconnect the Lun. My question is: which behaviour SHOULD I expect - is the SLES10 behavior correct (retry 60 times, and then create an error); or is the SLES11 behavor correct (wait infinitely), if I use the default settings for a Clariion? TIA D. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
