Load balancing in Open VMS V7.3-1

kirk.reindl_at_osioutsourcing.com
Date: 02/25/04 

Date: 25 Feb 2004 12:33:37 -0800

Hello:

I have a some general questions on how OpenVMS 7.3-1 handles load
balancing.
I understand that VMS spreads the disks across fibre controllers and
that the load balancing is not dynamic as far as work load. IE, the
disks get assigned to a card/channel at boot, and remain there unless
a failure happens or someone manually changes the path.

Currently I have a server that has all but one of its' disks assigned
to one controller. In my case PGA0. I don't know why all the disks
are going to PGA0. I can see my PGB0 card at the OS level without any
problems.

This is what I'd like to know:

1. Where does VMS make the config to "set" any disks to a particular
channel? I checked "mount_disks.com" but there are no set commands.
When I do a show dev d /mount and look at the mounted disks, it
appears to me that VMS is taking the first half of disks and assigning
on one channel and assigning the other half on another channel. (In
other words it doesn't appear to be assigning in a alternating
fashion)

2. If I manually attempt to assign a disk to a channel, let's say:
set dev $1$dga355:/switch/path=pgb0 will I cause an
interruption/outage to that disk? I'm new to VMS and a little nervous.

3. Can you give any explaination on why VMS wouldn't have balanced
the disk on my last boot? I'm looking for ways to investigate this.
Can you direct me to a boot log?

Thanks for your comments and suggestions.

Below is some output that shows my situation:

OSIJX2> show dev /multi
Device Device Error Current
 Name Status Count Paths path
$1$DGA16: (OSIJX2) Online 0 3/ 3
PGB0.5006-0482-BCC3-0A5A
$1$DGA17: (OSIJX2) Online 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA351: (OSIJX2) ShadowSetMember 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA353: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA355: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA357: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA360: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA362: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA365: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA366: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA373: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA377: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA381: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA383: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA385: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA387: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
$1$DGA388: (OSIJX2) Mounted 0 3/ 3
PGA0.5006-0482-BCC3-0A45
OSIJX2>

OSIJX2> show dev fg0 /full

Device FGA0:, device type KGPSA Fibre Channel, is online, shareable,
error
    logging is enabled.

    Error count 0 Operations completed
       0
    Owner process "" Owner UIC
[SYSTEM]
    Owner process ID 00000000 Dev Prot
S:RWPL,O:RWPL,G,W
    Reference count 0 Default buffer size
       0
    Current preferred CPU Id 2 Fastpath
       1
    Current Interrupt CPU Id 2
    FC Port Name 1000-0000-C924-571D FC Node Name
2000-0000-C924-571D

Device FGB0:, device type KGPSA Fibre Channel, is online, shareable,
error
    logging is enabled.

    Error count 0 Operations completed
       0
    Owner process "" Owner UIC
[SYSTEM]
    Owner process ID 00000000 Dev Prot
S:RWPL,O:RWPL,G,W
    Reference count 0 Default buffer size
       0
    Current preferred CPU Id 0 Fastpath
       1
    Current Interrupt CPU Id 0
    FC Port Name 1000-0000-C92A-68AF FC Node Name
2000-0000-C92A-68AF

OSIJX2>
OSIJX2> show dev dga16 /full

Disk $1$DGA16: (OSIJX2), device type EMC SYMMETRIX, is online,
file-oriented
    device, shareable, device has multiple I/O paths, served to
cluster via MSCP
    Server, error logging is enabled.

    Error count 0 Operations completed
    2292
    Owner process "" Owner UIC
[SYSTEM]
    Owner process ID 00000000 Dev Prot
S:RWPL,O:RWPL,G:R,W
    Reference count 0 Default buffer size
     512
    WWID 01000010:6006-0480-0001-8370-0521-4754-4B30-3130
    Host name "OSIJX2" Host type, avail AlphaServer
ES40, yes
    Alternate host name "OSIJX1" Alt. type, avail AlphaServer
ES40, yes
    Allocation class 1

  I/O paths to device 3
  Path PGA0.5006-0482-BCC3-0A45 (OSIJX2), primary path.
    Error count 0 Operations completed
       0
  Path PGB0.5006-0482-BCC3-0A5A (OSIJX2), current path.
    Error count 0 Operations completed
    2292
  Path MSCP (OSIJX1).
    Error count 0 Operations completed
       0

OSIJX2>
OSIJX2> show dev $1$DGA353 /full

Disk $1$DGA353: (OSIJX2), device type EMC SYMMETRIX, is online,
mounted, file-
    oriented device, shareable, device has multiple I/O paths, served
to cluster
    via MSCP Server, error logging is enabled.

    Error count 0 Operations completed
60653750
    Owner process "" Owner UIC
[SYSTEM]
    Owner process ID 00000000 Dev Prot
S:RWPL,O:RWPL,G:R,W
    Reference count 107 Default buffer size
     512
    Current preferred CPU Id 2 Fastpath
       1
    WWID 01000010:6006-0480-0001-8370-0521-4441-5431-3631
    Total blocks 35354880 Sectors per track
      64
    Total cylinders 36828 Tracks per cylinder
      15
    Host name "OSIJX2" Host type, avail AlphaServer
ES40, yes
    Alternate host name "OSIJX1" Alt. type, avail AlphaServer
ES40, yes
    Allocation class 1

    Volume label "TEL" Relative volume number
       0
    Cluster size 18 Transaction count
     107
    Free blocks 25869996 Maximum files allowed
  935694
    Extend quantity 5 Mount count
       2
    Mount status System Cache name
"_DSA100:XQPCACHE"
    Extent cache size 64 Maximum blocks in extent cache
 2586999
    File ID cache size 64 Blocks in extent cache
 1244538
    Quota cache size 0 Maximum buffers in FCP cache
    4240
    Volume owner UIC [TELS,*] Vol Prot
S:RWCD,O:RWCD,G:RWCD,W:RWCD

  Volume Status: ODS-2, subject to mount verification, write-back
caching
      enabled.
  Volume is also mounted on OSIJX1.

  I/O paths to device 3
  Path PGA0.5006-0482-BCC3-0A45 (OSIJX2), primary path, current path.
    Error count 0 Operations completed
60653750
  Path PGB0.5006-0482-BCC3-0A5A (OSIJX2).
    Error count 0 Operations completed
       0
  Path MSCP (OSIJX1).
    Error count 0 Operations completed
       0

OSIJX2>

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