Sun Storage 3511 SATA Array
 
Sun Storage 3510 FC Array
 
Sun Storage Traffic Manager Software
 

PLA-Support>Sun Systems>DISK>Arrays>SN-DK: SE31xx_33xx_35xx
 
_Old GCS Categories>Sun Microsystems>Storage - Disk>Modular Disk - 3xxx Arrays
 
_Old GCS Categories>Sun Microsystems>Storage Software>Storage Resource Management
 

MPxIO pairs-off ESI device seen on one channel with disk device (LUN 0) seen on other channels.

Applies to:

Symptoms

A Logical Drive (LD) is mapped as LUN 0 on multiple channels.

After unmapping the LD on one channel, the Sun Storage 351x FC Array will present an ESI device as
LUN 0. MPxIO will pair off this new ESI device with the remaining LUNs of the LD on the other channel.

When the host looses access to the LD , format displays it as:

    1. c8t600C0FF00000000000660D1AE0FCA401d0 

/scsi_vhci/ssd@g600c0ff00000000000660d1ae0fca401

Detailed Example of the Symptom:

Three Sun Storage 351x FC Array partitions are mapped on channel 0 and 4. MPxIO is enabled:

# cfgadm -al -o show_SCSI_LUN

Ap_Id                          Type         Receptacle   Occupant     Condition

c2                             fc-private   connected    configured   unknown

c2::256000c0ffc0660d,0 disk connected configured unknown c2::256000c0ffc0660d,1 disk connected configured unknown c2::256000c0ffc0660d,2 disk connected configured unknown

c3                             fc           connected    unconfigured unknown

c4                             fc-private   connected    unconfigured unknown

c5                             fc-private   connected    configured   unknown

c5::216000c0ffc0660d,0 disk connected configured unknown c5::216000c0ffc0660d,1 disk connected configured unknown c5::216000c0ffc0660d,2 disk connected configured unknown

LUN 0 is mapped on channel 0 and 4 of the 351x array.
The disk is seen from the host (by the format command) and labeled using type 0
(Auto configure). LUNs can be used without any problem.

Then all LUNs on channel 4 are unmapped. The SE351x presents an ESI device to the host
on channel 4.

# cfgadm -al -o show_SCSI_LUN

Ap_Id                          Type         Receptacle   Occupant     Condition

c2                             fc-private   connected    configured   unknown

c2::256000c0ffc0660d,0 ESI connected configured unknown

c3                             fc           connected    unconfigured unknown

c4                             fc-private   connected    unconfigured unknown

c5                             fc-private   connected    configured   unknown

c5::216000c0ffc0660d,0         disk         connected    configured   unknown

c5::216000c0ffc0660d,1         disk         connected    configured   unknown

c5::216000c0ffc0660d,2         disk         connected    configured   unknown

 In format, the LUN 0 is now shown and cannot be labeled.
LUN 0 is unusable while luns 1 and 2 are working fine.

# format

Searching for disks...done

AVAILABLE DISK SELECTIONS:

0. c0t0d0 

/pci@1f,4000/scsi@3/sd@0,0

1. c8t600C0FF00000000000660D1AE0FCA401d0 

/scsi_vhci/ssd@g600c0ff00000000000660d1ae0fca401

2. c8t600C0FF00000000000660D1AE0FCA403d0 

/scsi_vhci/ssd@g600c0ff00000000000660d1ae0fca403

3. c8t600C0FF00000000000660D0431530F00d0 

format> type

AVAILABLE DRIVE TYPES:

0. Auto configure

........

22. other

Specify disk type (enter its number): 0

Auto configure failed

format> quit

From luxadm display, it looks like MPxIO paired off the ESI device on channel 4,
and the LUN 0 on channel 0. It still reports both channels as online, even though
there is only one channel left.

# luxadm display /dev/rdsk/c8t600C0FF00000000000660D1AE0FCA401d0s2

DEVICE PROPERTIES for: /dev/rdsk/c8t600C0FF00000000000660D1AE0FCA401d0s2

Vendor:               SUN

Product ID:           StorEdge 3511

Revision:             413C

Serial Num:           00660D000000

Unformatted capacity: 500000.000 MBytes

Write Cache:          Enabled

Read Cache:           Enabled

Minimum prefetch:   0x0

Maximum prefetch:   0xffff

Device Type:          SES device

Path(s):

 /dev/rdsk/c8t600C0FF00000000000660D1AE0FCA401d0s2

/devices/scsi_vhci/ssd@g600c0ff00000000000660d1ae0fca401:c,raw

Controller           /devices/pci@1f,4000/SUNW,qlc@2/fp@0,0

Device Address              256000c0ffc0660d,0

Host controller port WWN    210000e08b0aafaf

Class                       primary

State                       ONLINE

Controller           /devices/pci@1f,4000/pci@4/SUNW,qlc@5/fp@0,0

Device Address              216000c0ffc0660d,0

Host controller port WWN    210000e08b098b2e

Class                       primary

State                       ONLINE

For LUN 1, luxadm is reporting one channel as online, the other as offline.

# luxadm display /dev/rdsk/c8t600C0FF00000000000660D1AE0FCA403d0s2

DEVICE PROPERTIES for disk: /dev/rdsk/c8t600C0FF00000000000660D1AE0FCA403d0s2

Vendor:               SUN

Product ID:           StorEdge 3511

Revision:             413C

Serial Num:           00660D1AE0FC

Unformatted capacity: 768951.000 MBytes

Write Cache:          Enabled

Read Cache:           Enabled

Minimum prefetch:   0x0

Maximum prefetch:   0xffff

Device Type:          Disk device

Path(s):

 /dev/rdsk/c8t600C0FF00000000000660D1AE0FCA403d0s2

/devices/scsi_vhci/ssd@g600c0ff00000000000660d1ae0fca403:c,raw

Controller           /devices/pci@1f,4000/SUNW,qlc@2/fp@0,0

Device Address              256000c0ffc0660d,1

Host controller port WWN    210000e08b0aafaf

Class                       primary

State                       OFFLINE

Controller           /devices/pci@1f,4000/pci@4/SUNW,qlc@5/fp@0,0

Device Address              216000c0ffc0660d,1

Host controller port WWN    210000e08b098b2e

Class                       primary

State                       ONLINE

Cause

This situation arises when no logical drive is mapped as LUN0.

Solution

To recover from this situation a reboot of the host is required.

There are two ways available to anticipate the occurence of this problem.

1. For LUN 0 devotees:

Create small dummy partitions for both SE351x controllers and map them as
LUN 0 on all channels. Do not use LUN masking for those LUN 0, as all hosts
need to see them. Do not touch those LUNs any more. Leaving those LUN 0s
available all the time prevents the presentation of ESI devices as LUN 0.

2. For all others:

Do not use LUN 0 for the mapping of LDs at all. The SE351x will present ESI
devices as LUN 0 on all channels in the case when nothing is mapped to LUN 0. A LUN 0
is required to comply with the SCSI standard. The problem only occurs
when unmapping a LUN 0. Therefore not mapping an LD to LUN 0 makes it
difficult to trigger the problem.

minnow, SE3511, mpxio, drive type unknown, lun 0

Change History
Date: 2010-12-20
User Name: susan.copeland@oracle.com
Action: Address Comments (add 3510)

This solution has no attachment