Determining order in which disks are bound in RAID 1/0 group

Product:

 

CLARiiON

 

Description:

 

Determining order in which disks are bound in RAID 1/0 group

 

Fix

 

From the example using Navisphere Manager during RAID group creation, manually select drives in the following order: 0_0_0, 1_0_0, 0_0_1, 1_0_1 and then during binding RAID 1/0 LUN, a relationship of primary disk 0_0_0 to secondary disk 1_0_0 and primary disk 0_0_1 to secondary disk 1_0_1 will be established. 


The same will hold true when executing a navicli createrg command (or naviseccli createrg). With all of these commands, naviseccli can be used instead of navicli for CLARiiONs of Release 19 or higher.  The order in which you list disks in the command line will determine the primary/secondary relationship. However, the navicli getrg command will list the disks in the RAID group in a different order than Navisphere Manager. Navisphere CLI accurately lists all primary disks first, then all secondary disks but does not identify them as such. The pairing of the disks is preserved in the presentation if you take the different ordering schemes into account but the presentation of the data can be misleading.


In an SPcollect file the navicli getrg shows the following:


List of disks: Bus 0 Enclosure 4 Disk 5           <-- Primary 1
  Bus 0 Enclosure 4 Disk 7     <-- Primary 2
  Bus 0 Enclosure 4 Disk 9     <-- Primary 3
  Bus 1 Enclosure 4 Disk 6     <-- Primary 4
  Bus 1 Enclosure 4 Disk 8     <-- Primary 5
  Bus 0 Enclosure 4 Disk 6     <-- Secondary 1
  Bus 0 Enclosure 4 Disk 8     <-- Secondary 2
  Bus 1 Enclosure 4 Disk 5     <-- Secondary 3
  Bus 1 Enclosure 4 Disk 7     <-- Secondary 4
  Bus 1 Enclosure 4 Disk 9     <-- Secondary 5


Where "Primary" or "Secondary," which is not shown in output, is included here to describe the primary/secondary relationship.

Navisphere CLI accurately lists all primary disks first, then all secondary disks, but does not identify them as such. The pairing of the disks is preserved in the presentation if you take the different ordering schemes into account. However,  the presentation of the data can be misleading.

Verifying the primary to secondary relationship once RAID 1/0 LUNs are created cannot be done using Release 11 (Navisphere 6.4) and earlier versions of Navisphere Manager browser or Navisphere CLI. With Release 12 and newer versions, if you are creating a RAID group, you create the RAID group in the following manner:


navicli -h <SP_IP_ADDRESS> createrg <RG#> P1 S1 P2 S2 ......

Note: The example shown does not include options that you may want to include.

The P1 / S1 are defined as primary disk 1 and secondary disk 2 with the format for the disk being B_E_D (bus, enclosure, disk).  Run the getrg command and something similar to this will be seen:

navicli -h <SP_IP_ADDRESS> getrg 100

RaidGroup ID:       100
RaidGroup Type: Unbound                    <- Displays as unbound, but note how disks are listed.
List of disks: Bus 0 Enclosure 0  Disk 0        <- Primary 1
  Bus 1 Enclosure 0  Disk 0  <- Secondary 1
  Bus 0 Enclosure 0  Disk 1  <- Primary 2
  Bus 1 Enclosure 0  Disk 1  <- Secondary 2
  Bus 0 Enclosure 0  Disk 2  <- Primary 3
  Bus 1 Enclosure 0  Disk 2  <- Secondary 3
List of LUNs:        Not Available
Legal RAID types:    r5 r0 r1_0                 <- Note that different RG types are available.

Now perform the BIND operation for the LUNs:

navicli -h <SP_IP_ADDRESS> bind r1_0 <LUN#> -rg <RG#> <any options for the RG>

navicli -h <SP_IP_ADDRESS> bind r1_0 0 -rg 100 -sq mb -cap 10 -sp a

Take a look at the getrg output again: 

navicli -h 10.5.43.206 getrg 100

RaidGroup ID:      100
RaidGroup Type:    r1_0
List of disks:     Bus 0 Enclosure 0  Disk 0 <- Primary 1
Bus 0 Enclosure 0  Disk 1        <- Primary 2
Bus 0 Enclosure 0  Disk 2        <- Primary 3
Bus 1 Enclosure 0  Disk 0        <- Secondary 1
Bus 1 Enclosure 0  Disk 1        <- Secondary 2
  Bus 1 Enclosure 0  Disk 2 <- Secondary 3
List of LUNs:      0             <- Note that a LUN number is shown .

Notice how the list of disks is reordered and now shows the RAID Group type as R1/0.  So prior to binding any LUNs, the RAID Group shows the listing in one manner.  Once you bind LUNs into the RAID group type, the ordering is listed differently. Creation of the RAID Group using the Navisphere GUI has the same affect. You select the LUNs as you want them to end up bound as R1/0. Therefore, select P1, S1, P2, S2, …to move them to the right-hand window.

If you want to alternately confirm the correct order of disks, execute an SPcollect that is available via Navisphere CLI. This SPcollect script runs and collects a command output (lustat) that enables you to identify primary and secondary disks also. You can also establish an EMCRemote (SymmRemote) connection to a storage processor and obtain this same output using an engineering-level command. A request for enhancement has been requested to make this information visible through use of Navisphere CLI. Contact the EMC Support for assistance in obtaining the primary/secondary information if you cannot run an SPcollect script. Cite this solution ID (emc59462).


The  lustat command, also in an SPcollect file, shows the following:


Logical Unit Summary:

RAID LUN Dflt. Unit

LUN  Group Attr. Owner Type    Capacity   Cache  State FRUs
---- ----- ----  ------ ------- --------   ----- ----- ----------------
5    1     G SP-A RAID-10     120.0 GB  RW- ENA   4 5 127 128
FRU 4 is the first primary
FRU 5 is the second primary
FRU 127 is the first secondary (to fru 4)
FRU 128 is the second secondary (to fru 5)


You can also establish an EMCRemote (SymmRemote) connection to a storage processor and then run an engineering-level command. A request for enhancement has been requested to make this information visible through use of Navisphere CLI. Contact the EMC Support for assistance in obtaining the primary/secondary information if you cannot run an SPcollect script. Cite this solution ID (emc59462).

 

For more information, Refer EMC Knowledgebase article emc59462