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Max Targets and LUNs on A5158

 
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John Thykattil
Occasional Contributor

Max Targets and LUNs on A5158

Hi -

I have hpux 11.00 on V2600s with A5158 fibre channel adapters soon to be used on switched fabric environment.

What are the max targets and LUNs I can have per HBA? I heard it was max 16 targets and 8 LUNs per HBA, but I thought with virtual buses and volume set addressing, I can get a lot more targets or LUNs.

Thanks.

John
6 REPLIES 6
Steven E. Protter
Exalted Contributor

Re: Max Targets and LUNs on A5158

That depends on what kind of switch and what kind of disk array you are connecting to. EMC has a higher limit as does HP disk arrays.

I work with Xiotech which depending on Fibre card has the exact same limit. There was only one HP Fibre card available when we did this project.

There is supposed to be a fix under development for this on the driver side.

SEP
Steven E Protter
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avsrini
Trusted Contributor
Solution

Re: Max Targets and LUNs on A5158

Hi John,
Yes by using VSA, you can have 2^14 = 16384 Addressable LUN's.
You can use Volume set addressing for XP, VA-*, FC60 and EMC disk arrays.

check the following link for more info.

http://www2.itrc.hp.com/service/iv/docDisplay.do?docId=/DE_SW_UX_swrec_EN_01_E/FibreChannel.pdf


Rgds
Srini.


Be on top.
Ross Zubritski
Trusted Contributor

Re: Max Targets and LUNs on A5158

John,

A Symm will only support 256 LUNS per channel.

Regards,

RZ
John Thykattil
Occasional Contributor

Re: Max Targets and LUNs on A5158

I will have a brocade fabric environment with HDS 9980 . From reading the HDS doco, my understanding is that I map AL-PA to TIDs. Here is the document text from Appendix A:
-----------------------------------
"The host maps SCSI protocol to fibre-channel protocol and detects and accesses fibreconnected
devices using device files (/dev/dsk/c*t*d* and /dev/rdsk/c*t*d*) in the same way
as for SCSI-connected devices. The device files for fibre-connected devices are configured in
a different way than SCSI-connected devices, because fibre supports 126 addresses per path
while SCSI supports 16 TIDs per path.
Table A.1 identifies the fixed mappings between the TID values assigned by the HP-UX??
system and the FC native addresses (AL_PA/SEL_ID) for FC adapters. For each device file
(/dev/dsk/c*t*d*), the c value is the adapter number, and the t value is the target ID. The c
value depends on the server configuration; a different value is assigned per each column of
Table1"
------------------------------------------
The way I read this is: per HBA, it seems that there will be eight virtual controllers, each with 16 TIDs and each TID with 8 LUNs except 1 TID, which will only have 6 LUNs. That's a total of 126 target IDs each with 8 LUNs. So that adds up to 1008 LUNs I can address via a single A5158. I know that the HDS can only assign upto 512 devices behind one of it's own front end channels. But can't I always assign disks from multiple front-end channels to my single HBA via LUN security methods?

Also, how are the controller, target and LUNs going to show up on my system and how are they going to be numbered? I will have up to 8 HBAs (A5158) with groups of LUNs assigned to two HBAs, for alternate links? I am trying to document all the device files ahead of time. I can't seem to find any doco out there that goes over this.

Thanks.

John
John Thykattil
Occasional Contributor

Re: Max Targets and LUNs on A5158

Thanks Srini -

Very greatful for the info; it looks like what I am looking for.

John
Karthik S S
Honored Contributor

Re: Max Targets and LUNs on A5158

Hi,

I am having the same problem now. We have 2 A class servers connected to VA7100 via FC Switch fabric. Initially the VA7100 had 7 LUNs of size 1GB each and both the servers were able to see all the LUNs through ioscan. (even after a reboot or insf -e) Now that I created 2 more LUNs on the VA but the servers are not able to see them. These servers have PCI FC A5158 HBAs. How do I solve this problem.

Pl. help

Thanks,
Karthik S S
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