A common task in a sysadmin’s life is to assist to the changes which are affecting the SAN network. At smaller organizations it could be that besides the system administrator role you also need to manage the storage side. So here’s a post which might help you if you need to check the status of the LUN paths. For checking the availability of the LUNs, you can use the ioscan command like this:
# ioscan -P health -C disk Class I H/W Path health =============================== disk 1 64000/0xfa00/0x1 online disk 4 64000/0xfa00/0x6 online disk 7 64000/0xfa00/0x7 online disk 10 64000/0xfa00/0x8 online disk 13 64000/0xfa00/0x9 online disk 16 64000/0xfa00/0xa online disk 19 64000/0xfa00/0xb online ...
In the above output you can see these health conditions:
- online
- offline
- limited
- disabled
Online means that all the paths are usable. However this does not necessary mean that all the paths are active. In case you are using active/passive multipathing only one path is active, the others are in stanby state. Offline means that the specific LUN is not accessible on either of its paths. If you see limited health, then then the LUN is not on all the paths are accessible. Disabled means that the LUN has been suspended as a result of some sort of error.
If you see a limited health in the above output, you might want to know qith which path you have problems. It’s easy to list the health status for each paths:
# ioscan -P health -C lunpath Class I H/W Path health =============================== lunpath 0 0/0/0/2/0/0/0.0x0.0x0 online lunpath 1 0/0/0/2/0/0/0.0x0.0x4000000000000000 online lunpath 2 0/0/0/5/0/0/0.0x50014380113737e8.0x0 online lunpath 4 0/0/0/5/0/0/0.0x50014380113737e8.0x4001000000000000 online lunpath 6 0/0/0/5/0/0/0.0x50014380113737e8.0x4002000000000000 standby lunpath 8 0/0/0/5/0/0/0.0x50014380113737e8.0x4003000000000000 online lunpath 10 0/0/0/5/0/0/0.0x50014380113737e8.0x4004000000000000 online lunpath 13 0/0/0/5/0/0/0.0x50014380113737e8.0x4005000000000000 standby lunpath 15 0/0/0/5/0/0/0.0x50014380113737e8.0x4006000000000000 online lunpath 16 0/0/0/5/0/0/0.0x50014380113737e8.0x4007000000000000 standby lunpath 18 0/0/0/5/0/0/0.0x50014380113737e8.0x4008000000000000 online lunpath 20 0/0/0/5/0/0/0.0x50014380113737e8.0x4009000000000000 standby lunpath 23 0/0/0/5/0/0/0.0x50014380113737e8.0x400a000000000000 online lunpath 24 0/0/0/5/0/0/0.0x50014380113737e8.0x400b000000000000 standby ...
The health column in the above output may have the following values:
- online
- offline
- unusable
- disable
- standby
Online is self-explanatory, just as offline. Unsable means that the lunpath authentication has failed. You get a disable status if a lunpath has been suspended because of an error. And finally you’ll see a standby status for all the LUNs which are accessible through an active/passive policy.
Note that the above checks are only valid if you are using the new mass storage stack which was introduced in 11iv3. If you are using legacy DSFs or have an older HP-UX version then you either use some software for multipathing (like HP Secure Path, EMC PowerPath or whichever SW comes with your storage), or multipathing is done by your volume manager (like LVM or VxVM) or you don’t use multipathing at all. In these cases you should have to figure out the method to check the paths (or you can search on this blog maybe I already wrote a post about that method, like this EMC cheatsheet.)
