Wednesday, May 29, 2013

How to scan and detect new luns in Linux (Veritas and EMC)

When new luns are become available for the server they are not being picked up automatically.
Simplest way - reboot the box.
More elegant way - scan for new luns and add them to existing configuration online.

On most of the distributions you may find script which is responsible for triggering rescan.

Next - verify the current config - check how many luns are currently configured:
# powermt display
Symmetrix logical device count=121
CLARiiON logical device count=0
HP xp logical device count=0
Ess logical device count=0
Invista logical device count=0
---- Host Bus Adapters ---- ---- I/O Paths -----  ------ Stats -----
###  HW Path               Summary   Total   Dead  IO/Sec Q-IOs Errors
   2 lpfc                  optimal     242      0       -     0      0

   3 lpfc                  optimal     242      0       -     1      0

For more detailed output you may run:
# powermt display dev=all

To detect new luns and add them to the configuration run:
# powermt config
# powermt save
# powermt display
You should now see a more luns in the output.

Additionally if you're using Veritas Storage Foundation you may scan for new disk devices by triggering:
# vxdisk scandisks new
New devices will be visible and in "error" state (you will need to initialize them later):
# vxdisk -o alldgs list
DEVICE       TYPE            DISK         GROUP        STATUS
cciss/c0d0   auto:none       -            -            online invalid
emcpowera   auto:cdsdisk    -            (datadg)  online
emcpowerb    auto:cdsdisk    -            (datadg)  online
emcpowerc   auto:cdsdisk    -            (datadg)  online
emcpowerd   auto:cdsdisk    -            (datadg)  online
emcpowere   auto:cdsdisk    -            (datadg)  online
emcpowerf   auto            -            -            error
emcpowerg   auto            -            -            error
emcpowerh   auto            -            -            error
emcpoweri   auto            -            -            error

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