How do you create a properly aligned LUN?

[droach]

Ok, I thought I was creating aligned LUNs, now I am not so sure. 

Currently running OnTap rel 8.0.2 7-Mode on an nSeries with a mix of FC and SATA disks.  Anyone familiar with the subject of alignment knows about the various levels where misalignment can occur.  From everything I have read, the lower levels of alignment are handled for you when creating aggregates, volumes, and LUNS, and the only place you need to be concerned is when you create the OS disks and partitions for your servers or VM's.  Here is a snippet from the Best Practice guide:

N series systems automate the alignment of VMFS with N series iSCSI, FC and FCoE LUNs. This task is automated during the LUN provisioning phase of creating a datastore, when you select the LUN type VMware for the LUN.

Using the NetApp System Manager GUI to create LUNS and volumes I assumed that they were being created with the proper alignment.  All I have to do is select 'vmware' or Windows' when creating the LUN.  But, when I go into advanced mode and issue the command:

    lun show -v

almost every one of the LUNS show as "misaligned".  Here is what they look like:

Couldn't find any info on this command's output in 'advanced' mode so I am not sure what this is telling me.  Is is safe to assume that this command is showing that the lower levels of the alignment are what is misaligned?  If so, why are they misaligned?

Thanks,

D

[bjornkoopmans]

Hi,

We are having the exact same thing. When running diagnostics in Performance Advisor, it also tells me than practically all my LUN's are misaligned, even though I always create them using SnapDrive for Windows, or from vCenter (using respectively 'windows_2008' and 'vmware' for the volume).

Anyone any idea?

[bhanojiisit]

na_check_lun_alignment - Realtime Tool to Monitor LUN Alignment

This script allows you to monitor a filer for unaligned LUN access.

Just enter the filername as an argument to this script or executable.

The script will periodically check the output of the "stats show lun"

command on the filer, and present the results as follows:

Example output:

READ   WRITE   RBUCKETS  WBUCKETS  LUN
??      OK    ????????  X???????  /vol/VMWare1/VMware1/ws03-exch07-h.lun-hoiMlZO606yH
OK      OK    X???????  X???????  /vol/Temp/Temp/ws03-exch07-n.lun-hoiMlZOBJU8w
OK      OK    X???????  X???????  /vol/SQLData2/SQLData2/ws03-sql17-g.lun-hoiMlZOBJKtu
??      OK    ????????  X???????  /vol/SQLData1/SQLData1/ws03-sql17-i.lun-hoiMlZO60FB0
??      !!    ????????  ????X???  /vol/ExchStorageGroup5/ExchStorageGroup6/ws03-exch07-k.lun-hoiMlZO60VEU
OK      !!    X???????  XXXXXXXX  /vol/ExchLog/ExchLog/ws03-exch07-l.lun-hoiMlZCo3/mn
OK      OK    X???????  X???????  /vol/ExchStorageGroup3/ExchStorageGroup3/ws03-exch07-j.lun-hoiMlZO60LNx
??      OK    ????????  X???????  /vol/ExchStorageGroup4/ExchStorageGroup4/ws03-exch07-m.lun-hoiMlZO60aOA
??      OK    ????????  X???????  /vol/ExchPub/ExchPub/ws03-exch07-f.lun-hoiMlZCo3gtp
??      OK    ????????  X???????  /vol/ExchServacc/ExchServacc/ws03-exch07-q.lun-hoiMlZOL99aA
OK      OK    X???????  X???????  /vol/ExchStorageGroup2/ExchStorageGroup2/ws03-exch07-o.lun-hoiMlZOEyJmr
OK      OK    X???????  X???????  /vol/ExchStorageGroup1/ExchStorageGroup1/ws03-exch07-p.lun-hoiMlZOEyRPq

The READ and WRITE columns will contain "OK" if no unaligned access

has been observed for a LUN, "??" if no IO has been monitored yet.

Finally, "!!"" will be printed if unaligned access has been detected.

The other symbols represent read and write access in 512KB block

increments (8 x 512 KB = 4 KB blocks).