6TB storage expansion
Introduction
56 instead of 50TB are now available for the bioinformatics cluster. The tasks required to realize this extra space are:
- rescan multipath, details: multipath WWID; 36000d3100051f800000000000000016e (on mpathd)
Tools
listing
multipath -l
will give a useful if not very understandable list of characteristics. Most important, the device: dm-6 is noted, i.e.
mpathd (36000d3100051f800000000000000016e) dm-6 COMPELNT,Compellent Vol size=50T features='1 queue_if_no_path' hwhandler='0' wp=rw `-+- policy='round-robin 0' prio=0 status=active |- 6:0:0:1 sdd 8:48 active undef running |- 7:0:1:1 sde 8:64 active undef running |- 6:0:1:1 sdg 8:96 active undef running `- 7:0:2:1 sdf 8:80 active undef running
configuration
/etc/multipath.conf
Doesn't really have much. The only actives are:
defaults {
user_friendly_names yes
}
blacklist {
wwid 3600605b006c5f11019eadc840e589ae9
wwid 3600605b006a1af8019ee9a2d1036bfa7
wwid 3600605b006a1af801b46c4773d54b7d4
}
interpreter
There is also a interpreter available to query status and other things. To fire it up, type
multipathd -k
The
show maps topology
command in this interpeter will give you the same output as the "multipath -l" command. It mayy be necessary to find out more about the tool. For example, this command
paths count
gives 4 as the answer, which probably refers to sdd, sde, sdg, sdf mentioned in the above output. Indeed the
show devices
gives these four as the output. Unfortunately, there is nothign about rescanning here. I think this tool is at a higher-level than what is required for the rescanning, which seems to be a lower level jobs (multipath's understanding of "devices" gives this away somewhat).
Procedure
The rescan operation is most definitely required. Both Red Hat and Ubuntu guides give the same method of doing this
# echo 1 > /sys/block/device_name/device/rescan
However, under /sys/block/dm-6, there is no device subdirectory, and, needless to say, no rescan file. Mind, this is for SCSI.
Other sites repeat the recipe ad nauseam. There is no mention about whether this can in fact be done live.
