SCSI controller ids with EMC Symmetrix

[Darrell Allen]

Hi everyone,

My past experience with ServiceGuard has been with 2 node clusters using JBOD Jamaicas. On those I set the scsi controllers' id to 7 on one server and to 6 on the other.

Now I've got a Symmetrix. Each server has 3 scsi chains to different scsi directors on the Symm. In other words, I have 6 scsi chains (3 from each HP) to 6 scsi directors on the symm.

Do I still need to change the scsi controllers' id on one server? I wouldn't think so. Seems to me each scsi director is on a seperate scsi chain and the symm does it's magic internally.

Also, can anyone point me towards some good doc on using an EMC symm in a ServiceGuard cluster?

Thanks,
Darrell

[Duncan Edmonstone]

No you don't need to fiddle with the SCSI IDs of hour HBAs in this config.

This is a great little document on EMC configuration - it also covers ServiceGuard:

http://europe-support2.external.hp.com/cki/bin/doc.pl/sid=351cfdb800279f90c9/screen=ckiDisplayDocument?docId=200000055334321

Or if your in the US
http://us-support2.external.hp.com/cki/bin/doc.pl/sid=351cfdb800279f90c9/screen=ckiDisplayDocument?docId=200000055334321

HTH

Duncan

[Duncan Edmonstone]

Just noted something in that document that is out of date...

The LUN ordering no longer has to be sequential as long as you have the latest patch installed (can't remember the patch number, search the database for 'emc and sequential lun')

HTH

Duncan

[Roger Baptiste]

Darell,

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Are you using a switch to connect to the EMC or is it a direct connection from the Hostadaptor to the EMC ?? Not that it really matters in this case, but it is useful to make note off.

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Are you using FWscsi or Fibre card to connect to EMC?? I thought FWscsi was almost passe for HA disk connections. If possible, i would suggest moving to PCI fibre cards to hook to the EMCs. (tachlite cards ).

To answer your question: This being a cluster, it is preferable to have both the systems see the EMC similarly.
for eg: A lun being accessed as c10t5d1 on
system 1 should be seen with the same c10t5d1 on system 2.
This is not compulsory, but it helps in ease of maintenance of the system (VG's ) in the future.
How to do it: run ioscan -nfCext_bus and
check whether the cards on both the systems
show similar instance numbers (especially for the scsi connected to EMC). If they are not,
you would need to change them (that's a separate procedure involving changing the ioconfig file).

Once you make sure of this, the rest of the things will fall in place. You should be able to see similar disk paths on both boxes.
Yes, EMC presents lun internally and you don't need to do much about it. (unless you are also running SDR emc tool to present Luns to the system).

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Using EMC on a non-cluster environment is similar to that of a cluster environment.
The commands to use from the host end would be:

1) symmConsole -> provides GUI layout of emc disk conf . (very useful)

2)syminq (or inq) -> shows the LUNid and size
(useful to go along with ioscan -nkfCdisk and helps in the strategy to define PV's for a volume group)

3) sympd & symdev -> sympd shows what emc devices the system can see.

4) symcfg ls -> shows the Symmid's of the emc to which the host is connected.

All the above commands will be under /opt/emc. (do a find /opt/emc -name bin -type d and include the bin directories in your search path).

HTH
raj

[Darrell Allen]

Duncan, thanks for the info.

Raj, answers to your questions:

Direct connection from host adapter to EMC director.

I have FW scsi.

I agree, it's much easier to manage if the LUNs are presented as the same device path on each server. I've got some work to do there.

Yes, I'm running SDR.

Darrell

[Duncan Edmonstone]

If your device files aren't matching your in for some fun! Have a read of the man page for ioinit, paying particular attention to the -f option.

Typically what has to be done is re-ordering the instance numbers of the HBAs on the server to match up (thats the 'I' column on a 'ioscan -funC ext_bus')

Let us know if you need more help!

Duncan

[Darrell Allen]

Good help so far.

Anyone have a "gotcha" I need to look out for?

Thanks,
Darrell