[Lustre-discuss] LUN reassignment DDN and OSS

[syed haider]

All,
I recently raised a question about unbalanced OSTs and received the right
answer - increase the size of the OSTs. So I set forth to do this on
our DDN controllers and rather than having 32 1TB LUNs i decided to go with
4 8TB LUNs instead. In doing this I learned our LUNs were created
with the default 512 size and from reading the manual it appears it would
improve performance for our work to go with 4096. Since most jobs run
on lustre would be creating larger files (sequential) we're not concerned
about losing space from smaller files taking up a 4k block. Is there any
other concern I should have
with going with the larger block size?

Second question for the DDN expert- We have 4 OSS's connected to DUAL DDN
9550 controllers via fiber. With the older configuration we had
one 1TB LUN using one Tier so the lun output looked something like this:

         Logical Unit Status

                                         Capacity  Block
 LUN  Label        Owner  Status         (Mbytes)  Size  Tiers Tier list
-------------------------------------------------------------------------------
  0 lun 0            1    Ready            1120098   512    1  1
  1 lun 1            1    Ready            1120098   512    1  2
  2 lun 2            1    Ready            1120098   512    1  3
  3 lun 3            1    Ready            1120098   512    1  4
  4 lun 4            1    Ready            1120098   512    1  5
  5 lun 5            1    Ready            1120098   512    1  6
  6 lun 6            1    Ready            1120098   512    1  7
  7 lun 7            1    Ready            1120098   512    1  8
  8 lun 8            2    Ready            1120098   512    1  9
  9 lun 9            2    Ready            1120098   512    1  10


After making the change to only 4 LUNs two of my OSS's don't see any SCSI
devices when i run fdisk. By deleting and recreating the luns did I somehow
cause
a zoning issue? Thanks in advance.

Syed
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