connetrix (fiber switch) in HA configuration with same domain ID

[Ra Jose]

We have 2 64-ported fiber switch (connectrix).
These are configured as fcd domain id 97 (0x61).

Our hosts have 2 HBAs. Each HBA is connected to one port on each switch. So, each HBA goes to a separate switch.

These switches connect to symmetrix (dmx2000) on the backend.

powerpath is used on the hosts.

When I do ioscan -fC disk on the hp servers, for both HBA cards, I get this path
1/0/2/1/0/4/0.97.60.19.3.4.5
1/0/4/1/0/4/0.97.60.19.5.4.5

Usually, we see, second fiber switch configured as id=98 (0x62). So, the hp h/w path shows 98 in place of 97, avoiding confusion.

Now, the server is doing good. We have data going thru both HBAs (load balanced by powerpath).

My question is, whether this kind of switch configuraton is right, as you know, the switch are gives IDs 97 and 98? What kind of impact this has? If one of the switch goes down, then 97 is down, does it mean, all IO is stopped?

Thank you all.

Rajos

[Denver Osborn]

Since the connectrix siwtches aren't interconnected you're good to go. Confirm the HBA's are really on separate switches too.

If one switch goes down, you'll have lost just that one path... not both. You'd still have access to the devices through the good switch connected to your other hba.


-denver

[Steven E. Protter]

Shalom,

Don't trust us, run tests.

The configuration seems fine to me, but this is outside my area of core strength.

Tests:
1) See that there is no disruption while under load when one switch is turned off.
2) Same thing with switch 2.
3) Heavy load see that powerpath is balanced. http://www.hpux.ws/system.perf.sh to measure performance by device.

There may be more tests but I'm not the expert in this field, but I've been burned enough not to trust the experts. I test before production.

SEP

[Ra Jose]

Looks like, by hardware-wise, each hba goes to each switch, which is fine.

By software-wise, the switches have same domain-id (97 decimal). Since, powerpath is used, if one switch goes down, powerpath marks this path dead and use other path for data transfer.

Looks like there is no impact.

However, from what I know, the switches are given different domain ID, if only 2 switches are there. If there are 4 similar switches, one can combine 2 into each domain. The 2 switches domain, then can have same domain-id.

Ra Jos