Storage Foundation(SF) 5.0 MP3 introduces device name consistency

As configurations in data centers scale up and more SAN devices and nodes have to be managed, there is a greater need for consistency and predictability in device naming.

Storage Foundation (SF) supports two main device naming schemes - Operating System Native (OSN) naming and Enclosure Based Names (EBN)

Enclosure name consistency usually is not a problem, even when hosts are connected to multiple enclosures of the same type. The number of enclosures is small enough that consistency can be ensured through manual configurations.

Device indexing can be inconsistent as it does not consistently uniquely identify the device.

Volume Manager (VxVM) will sort the devices based on the LUN serial number (LSN) and uses the index to create the suffix for the device name. All nodes that see the same set of devices, will have the same sorted list, leading to some sort of consistent device indices across the cluster.

To overcome this limitation SF 5.0 MP3 introduces athird naming convention sometimes referred as "EBN_AVID" to enable device name consistency


EBN = Enclosure Based Naming
AVID= Array Volume Identifier


How the introduction of the AVID features makes life easier


With the introduction of thenew EBN_AVID naming scheme, identifying storage devices becomes far easier with consistent device naming across multiple nodes connected to the same storage and the disk access name will never change as it is based on the name defined at the array level.

When SF does not have access to a device AVID, it retrieves another unique LUN identifier called LUN serial number.

Finally, Storage Foundation supports a scalable framework allowing users to fully customize the device names on a host by applying a 'device naming file' that associates custom names with cabinet and LUN serial numbers.


# vxddladm getnamingscheme
NAMING_SCHEME PERSISTENCE LOWERCASEUSE_AVID
============================================================
EnclosureBased    Yes                  Yes                Yes


Note: EBN_AVID co-existence with EMC PowerPath controlled devices is not supported, therefore, the EBN_AVID naming convention is suppressed.


SF 5.0MP3 enables naming consistency in the following manner


Storage Foundation goes deeper into the storage arrays and discovers the short array volume identifiers (AVID) that are used for identification and management of array volumes on the storage managementconsole. The device index suffix of an EBN is set to match the discovered AVID.

This ensures consistency of the disk access name across all nodes connected to the same SAN device.

This makes the life of the system and storage administrators far easier than ever before.

AVIDs are usually hardware specific. On an EMC DMX array for example, the AVID value matches adevice's LUN id (SYMDEV) viewable from the EMC Solution Enabler SYMCLIinterface. Whilst on Hitachi (HDS) or HP XP storage arrays, the AVID equates to a device's CU:LDEV.


EMC DMX Array Example

The attached EMC DMX array has a Symmetrix id of "000290300822" for which can beshortened to "822"

# vxdmpadm listenclosure all
ENCLR_NAME        ENCLR_TYPE    ENCLR_SNO         STATUS          ARRAY_TYPE    LUN_COUNT
=======================================================================================
emc0                      EMC                  000290300 822      CONNECTED    A/A                    14
emc_clariion0          EMC_CLARiiON  CK200053300424  CONNECTED    CLR-A/PF          7
disk                        Disk                    DISKS                  CONNECTED    Disk                  3


The WWN value for the EMC symmaskdb command can be obtained from SFcommands "vxlist ctlr" and "vxdmpadm getctlr"


# vxlistctlr
TY   NAME   TYPE  STATE    WWN                      PNAME
hba  c1     FC     online  20:00:00:01:73:01:bb:eb  /pci@1e,600000/SUNW,jfca@2/fp@0,0
hba  c2     FC    online  -                        /pci@1c,600000/scsi@2

# vxdmpadm getctlr
LNAME    PNAME                                    VENDOR              CTLR-ID
=============================================================================================
c1        /pci@1e,600000/SUNW,jfca@2/fp@0,0        JNICorporation      20:00:00:01:73:01:bb:eb
c2        /pci@1c,600000/scsi@2                    -                    -


#echo "20:00:00:01:73:01:bb:eb" | tr -d":"
200000017301bbeb


# /opt/emc/SYMCLI/V6.5.1/bin/symmaskdb  -sid 822 list devs -wwn 200000017301bbeb

Symmetrix ID        :000290300822

Originator Port wwn : 200000017301bbeb
User-generatedName : rdgv240sol13/200000017301bbeb

SymDev                                              LUN
Name    Dir:P  Physical Device Name    VBUS  TID  SYMMHOST  Attr  Cap(MB)
------  -----  -----------------------  ----  ---  --------  ----  -------
0052    1C:0  rdmp/emc1_0052s2            0    0    fc    0          2015
0053    1C:0  rdmp/emc1_0053s2            0    0    fd    0          2015
0054    1C:0  rdmp/emc1_0054s2            0    0    fe    0          2015
0055    1C:0  rdmp/emc1_0055s2            0    0    ff    0          2015
008C    1C:0  rdmp/emc1_008cs2            0    0  10a    0           2015
008D    1C:0  rdmp/emc1_008ds2            0    0  10b    0           2015
008E    1C:0  rdmp/emc1_008es2            0    0  10c    0           2015
008F    1C:0  rdmp/emc1_008fs2            0    0  10d    0           2015
00E7    1C:0  rdmp/emc1_00e7s2            0    0    10  10          2158
           1C:1  rdmp/emc1_00e7s2            0    0    f    0           2158
00E8    1C:0  rdmp/emc1_00e8s2            0    0    11    0          2158
           1C:1  rdmp/emc1_00e8s2            0    0    c4  c4           2158
00E9    1C:0  rdmp/emc1_00e9s2            0    0    12  12          2158
           1C:1  rdmp/emc1_00e9s2            0    0    c5    0          2158
00EA    1C:0  rdmp/emc1_00eas2            0    0    13  13          2158
           1C:1  rdmp/emc1_00eas2            0    0    c6    0          2158
00EB    1C:0  rdmp/emc1_00ebs2            0    0    14  14          2158
           1C:1  rdmp/emc1_00ebs2            0    0    c7    0          2158
032D    1C:0  rdmp/emc1_032ds2            0    0    d2  d2  (M)    75000
           1C:1  rdmp/emc1_032ds2            0    0    e4    0  (M)    75000


The above EMC SYMDEV values correspond to the disk accessnames reported by Storage Foundation:

ie 032D equates to emc0_032d


# vxdisk -e -o alldgs list | grep emc0
emc0_00ea    auto:sliced    -            -          online              c1t5006048C5368E5A0d198s2 std
emc0_00eb    auto:cdsdisk  -            (bcvdg)     onlineudid_mismatch c1t5006048C5368E5A0d199s2bcv
emc0_00e7    auto:cdsdisk  emc0_00e7    bcvdg      online               c1t5006048C5368E580d16s2std
emc0_00e8    auto:sliced    -            -          online              c1t5006048C5368E5A0d196s2 std
emc0_00e9    auto:cdsdisk  -            -          online               c1t5006048C5368E580d18s2std
emc0_008c    auto:cdsdisk  d1           srdf2      online              c1t5006048C5368E580d266s2 srdf-r1
emc0_008d    auto:cdsdisk  d2           srdf2      online              c1t5006048C5368E580d267s2 srdf-r1
emc0_008e    auto:cdsdisk  d3           srdf2      online              c1t5006048C5368E580d268s2 srdf-r1
emc0_008f    auto:cdsdisk  d4           srdf2      online              c1t5006048C5368E580d269s2srdf-r1
emc0_032d    auto:sliced    rootdg01-s0  clone51dg  online              c1t5006048C5368E580d210s2 std
emc0_0052    auto:cdsdisk  EMC0_2      srdfdg      online              c1t5006048C5368E580d252s2 srdf-r1
emc0_0053    auto:cdsdisk  EMC0_14      srdfdg      online              c1t5006048C5368E580d253s2 srdf-r1
emc0_0054    auto:cdsdisk  EMC0_0      srdfdg      online              c1t5006048C5368E580d254s2 srdf-r1
emc0_0055    auto:cdsdisk  EMC0_1      srdfdg      online              c1t5006048C5368E580d255s2 srdf-r1


The disk access name can bepresented as uppercase or lowercase characters

# vxddladm setnamingscheme=ebn lowercase=no use_avid=yes


# vxdisk -e -oalldgs list | grep -i emc0
EMC0_00EA    auto:sliced    -            -          online              c1t5006048C5368E5A0d198s2 std
EMC0_00EB    auto:cdsdisk  -            (bcvdg)     onlineudid_mismatch c1t5006048C5368E5A0d199s2bcv
EMC0_00E7    auto:cdsdisk  emc0_00e7    bcvdg      online               c1t5006048C5368E580d16s2std
EMC0_00E8    auto:sliced    -            -          online              c1t5006048C5368E5A0d196s2 std
EMC0_00E9    auto:cdsdisk  -            -          online               c1t5006048C5368E580d18s2std
EMC0_008C    auto:cdsdisk  d1           srdf2      online              c1t5006048C5368E580d266s2 srdf-r1
EMC0_008D    auto:cdsdisk  d2           srdf2      online              c1t5006048C5368E580d267s2 srdf-r1
EMC0_008E    auto:cdsdisk  d3           srdf2      online              c1t5006048C5368E580d268s2 srdf-r1
EMC0_008F    auto:cdsdisk  d4           srdf2      online              c1t5006048C5368E580d269s2srdf-r1
EMC0_032D    auto:sliced    rootdg01-s0  clone51dg  online              c1t5006048C5368E580d210s2 std
EMC0_0052    auto:cdsdisk  EMC0_2      srdfdg      online              c1t5006048C5368E580d252s2 srdf-r1
EMC0_0053    auto:cdsdisk  EMC0_14      srdfdg      online              c1t5006048C5368E580d253s2 srdf-r1
EMC0_0054    auto:cdsdisk  EMC0_0      srdfdg      online              c1t5006048C5368E580d254s2 srdf-r1
EMC0_0055    auto:cdsdisk  EMC0_1      srdfdg      online              c1t5006048C5368E580d255s2 srdf-r1