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Port Allocation Class set-up

 
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Zbigniew Filek
Occasional Advisor

Port Allocation Class set-up

I need to set up Port Allocation Class for internal SCSI buses in our 3-node ES80 Fiber Channel cluster. I know I need to set the DEVICE_NAMING system parameter to 1 to enable "Port" alloclasses. How do I actually assign them to ports? The docs say they can be set up from MODPARAMS.DAT, but give no details. The only other info the manuals give is that SYSBOOT> set/class ddc n
can be used. How do I boot into SYSBOOT on ES80?
Thanks
16 REPLIES
Uwe Zessin
Honored Contributor
Solution

Re: Port Allocation Class set-up

The configuration is in SYS$SYSTEM:SYS$DEVICES.DAT:
+-----
$ type sys$system:sys$devices.dat
! SYS$DEVICES.DAT

! CLUSTER_CONFIG created 9-OCT-2002 10:46:18.94

[Port ATHENA$PKA]
allocation class = 11

[Port ATHENA$PKB]
allocation class = 12
$

+-----

For a conversational bootstrap (to get to SYSBOOT>), you need to set bit 1 in the lower longword of the boot flags. Assuming you are booting from [SYS0]:
>>> boot -flags 0,1

Assuming you are booting from [SYS3]:
>>> boot -flags 3,1

To view your boot configuration:
>>> show BOOT*
.
Zbigniew Filek
Occasional Advisor

Re: Port Allocation Class set-up

Thanks a lot. I'll give it a try on my next scheduled re-boot.
Ian Miller.
Honored Contributor

Re: Port Allocation Class set-up

the SET/CLASS commands at the SYSBOOT prompt writes SYS$SYSTEM:SYS$DEVICES.DAT

Do the conversational boot as described.
____________________
Purely Personal Opinion
Ian Miller.
Honored Contributor

Re: Port Allocation Class set-up

http://h71000.www7.hp.com/doc/82FINAL/aa-pv5mj-tk/00/00/33-con.html#portallocationclasseschanging
http://h71000.www7.hp.com/doc/82FINAL/aa-pv5mj-tk/00/00/33-con.html#portallocationclassesdesassigning

SYSBOOT> SET/CLASS PKB 152

Be sure that the DEVICE_NAMING parameter is set to 1 to enable new device-naming; for example:

SYSBOOT> SET DEVICE_NAMING 1

To deassign a port allocation class, enter the port name without a class number; for example:

SYSBOOT> SET/CLASS PKA
____________________
Purely Personal Opinion
Robert Brooks_1
Honored Contributor

Re: Port Allocation Class set-up

Unless you have connected together the internal SCSI buses of these systems, you don't *need* to set up port allocation classes. PACs are only needed for *shared* SCSI buses. If a systemwide allocation class is set up via the ALLOCLASS sysgen param, all local SCSI buses will use that value by default in the absence
of a PAC.

-- Rob
Zbigniew Filek
Occasional Advisor

Re: Port Allocation Class set-up

The buses are NOT connected. However, since Fibre Channel always uses allocation class one, all nodes in the cluster have also node-wide allocation class 1 and boot up with the two internal SCSI drives being assigned names $1$DKA0 and $1$DKB0 on all nodes. This causes device name duplication with all associated problems. In practice, the drives are accessible only on the Alpha that comes up last. These drives are not in use right now, since the cluster boots from a (shadowed)system disk on an EVA pair. After I fix the allocation classes I'll use them for page, swap and dump files (all the rest is on shadowed 2 EVAs)
Uwe Zessin
Honored Contributor

Re: Port Allocation Class set-up

The requirement that the host allocation class must match the device allocation class of an attached CI/DSSI node to be able to serve disks has been lifted some releases ago.
.
Robert Brooks_1
Honored Contributor

Re: Port Allocation Class set-up

The buses are NOT connected. However, since Fibre Channel always uses allocation class one, all nodes in the cluster have also node-wide allocation class 1 and boot up with the two internal SCSI drives being assigned names $1$DKA0 and $1$DKB0 on all nodes.

----

You do *not* need to set the allocation class to be 1 on all nodes. I have several clusters that use fibre channel storage where each node has a different alloclass (and no node has an alloclass of 1).

I would avoid using PACs unless absolutely necessary.

-- Rob (I/O Exec group of VMS Engineering)


Uwe Zessin
Honored Contributor

Re: Port Allocation Class set-up

I rather like PACs and since V7.2-1 it seems like they work quite well.

What I love to do is:
- assign host allocation classes in 10-increments
-- this gives unique device names for IDE CD-ROM
- assign PACs in 1-increments per controller letter
-- node1$PKA gives $11$DKA
-- node1$PKC gives $13$DKA
-- node2$PKB gives $12$DKA
- choose some other values for shared busses

That gives a neatly sorted list on
$ show device D
.
Willem Grooters
Honored Contributor

Re: Port Allocation Class set-up

IIRC, if you have a shared SCSI bus, all nodes that connect to it should do so on the same controller. Eg. NodeA connects to the bus over PKB, all other nodes that share the same bus must do so over PKB.

Willem
Willem Grooters
OpenVMS Developer & System Manager
Uwe Zessin
Honored Contributor

Re: Port Allocation Class set-up

It is not always possible to use the same host allocation class and the same controller letter (e.g. PKB) for a shared bus.

That is what port allocation classes (PACs) are for!!

Using a PAC creates a separate allocation class and sets the disk controller letter to "A" (e.g. $11$DKA, $37$DGA) no matter what controller letter the SCSI adapter uses (e.g. PGB, PGC).
.
Jan van den Ende
Honored Contributor

Re: Port Allocation Class set-up

Zbigniew,

let me start with:

WELCOME TO THE VMS FORUM!

To summ up the previous answers:

Robert Brooks pretty much defined it.

I would like to point out one thing he did not say explicitly:

AVOID a system alloclass of 1 if you do (intend to) have local disks also.

The arguments Uwe gives FOR using PACs are also quite valid, you should consider if they would have added (current or future) value for you.

--- and as a final addendum: what has been said about disks-on-fiber with alloclass 1 can be considered to also apply for tapes-on-fiber with TAPE_ALLOCLASS 2.

hth.

Proost.

Have one on me.

jpe



Don't rust yours pelled jacker to fine doll missed aches.
Thomas Ritter
Respected Contributor

Re: Port Allocation Class set-up

Our 4 node DT cluster we use allocation classes
20,21,22,23 for each node respectively. The disks are 1 and the tape drives are 2 giving a total of 6 allocation classes.
Robert_Boyd
Respected Contributor

Re: Port Allocation Class set-up

I'm surprised noone mentioned SYS$MANAGER:CLUSTER_CONFIG.COM yet. There is a section for managing Port Allocation Classes.

Menu sequence:

Change a cluster member's characteristics
-> Change 's shared SCSI port allocation class value

In some cases I've created the SYS$DEVICES.DAT file for one system using the CLUSTER_CONFIG procedure. Then I've copied the file to the other nodes in the cluster and edited the entries with TPU. In some cases I've created a cluster common version of the file that has all the entries for all the nodes of the cluster. Then I copy the file to all of the specific system directories.

Robert
Master you were right about 1 thing -- the negotiations were SHORT!
comarow
Trusted Contributor

Re: Port Allocation Class set-up

I thought I had written this.
Maybe I didn't hit submit.

A few minor comments on using port allocation class.

A non zero allocation class is required if you are going to shadow a disk.

While initial setting of a port allocation class can be set in cluster_config, afterward you are better off doing it at sysboot.

You set the class for the controller, not for the disk.
at sysboot
sysboot>set/class pka0 2


All shared busses must have the same allocation class.

I prefer having all local disks have a zero allocation class so the show up as
node$device, such as Filek$dka0:

If you are going to shadow, put each not into a group of numbers, such as 10s for one node, 20s for another. While this is not required, it will make management easier.

As far as booting into sysboot, the device must be presented to VMS and have a WWID number, and then b -fl root,1 device
as it shows up at the console.

Finally, using DEVICE_NAMING uses a newer, more stable algorythm.
Willem Grooters
Honored Contributor

Re: Port Allocation Class set-up

[quote]
All shared busses must have the same allocation class.
[/quote]

Hopefully not!
Should bre read as:

All nodes attached to a shared bus, should use the same allocation class for that bus.

That menas that if you have two shared busses on a system, each of them should have it's own PAC - but it should be the same on all connected systems.

For example:
Node CTRL1 PAC CTRL2 PAC
----- ----- --- ----- ---
NODEA PKA = 100 PKB = 110
NODEB PKA = 100 PKB = 110
NODEC PKA = 100 PKB = 110

and so on.

And yes: CLUSTER_CONFIG.COM can be used to set the port allocation class.

Willem

Willem Grooters
OpenVMS Developer & System Manager