topic XP512 Command Device in XP Storage

XP512 Command Device

Rene Sesink — Tue, 10 Jan 2006 04:28:50 GMT

Need W2K servers a command device to see other LUNs on a XP512?
We only see LUN's on W2k and W2003 servers when a XP512 Command Device is add to the LUN group.
Can anyone explane that.

Regards,
Rene

Re: XP512 Command Device

Fabian_Nowee — Tue, 10 Jan 2006 05:14:52 GMT

No, the commanddevice is only used for BC and CA purphoses.

Normaly when you map LUN's, you can group them as well as you can group WWN's. Finally you have to link them together (security).

Re: XP512 Command Device

Rene Sesink — Tue, 10 Jan 2006 06:55:53 GMT

Fabian,

Thanks for your fast responds.
When we add a LUN to a new W2k or W2k3 server,the new LUN is not seen after a rescan of new devices. We are using Emulex or Qlogic HBA together with SecurePath.
After adding the Command Device to the LUN group and do a rescan, all the LUN's are visible. This happend to all the windows servers. So all the W2k servers have a Command Device configured. Is this a normal behaviour?

Rene

Re: XP512 Command Device

Alzhy — Tue, 10 Jan 2006 08:51:26 GMT

A Command LUN in XP / Hitachi Lingo (Yes XP Arrays are Hitachi Arrays) is carved, presented and allocated just like any other LUN. However - it does not have an emulation or since its purpose is for business copy or Hitachi tools. It is also most often used as a communications channel as an "in-band" thing for tools like Performance Advisor.

Re: XP512 Command Device

Fabian_Nowee — Tue, 10 Jan 2006 11:12:17 GMT

Old driver? /firmware

Lun 0 issue? nowaday's drivers create a pseudo lun to scan additional luns wich are not initialy starting at 0. Maybe the commanddevice (yes same as in HDS 9960) is providing the missing lun 0.

Re: XP512 Command Device

Rene Sesink — Wed, 11 Jan 2006 03:00:24 GMT

Fabian,

We running the latest drivers, so the LUN 0 issue must be more usefull.
The Command devices LUN number is 0, and that makes the whole story very clear to me.
Lun 0 makes other LUN's visible to the Wintel servers. It works as a pseudo LUN.
Thanks for your support.

Rene