[Info-vax] MSA1000 / VMS / Linux

[Grant Taylor]

On 12/19/20 12:10 PM, Alan Frisbie wrote:
> I would like to share my MSA1000 between my VMS system(s) and Linux.

What does "share" mean in this context?  Specifically are you trying to 
share the same LUN(s) between VMS and Linux?  Or just different 
dedicated LUN(s) per client system?

> Has anyone here done this?

I have not.

> Can it be done at all?

If VMS is happy enough with the MSA1000 with multiple LUNs dedicated to 
specific client machines, I would expect so.

> Are there any problems I should look out for?

My concerns would be if the MSA1000 plays nice enough with the multiple 
dedicated LUNs to make VMS happy or not.

I expect that you are going to need to filter access to the different 
LUNs based on client host.  I don't know if the MSA1000 has the same 
capabilities when filtering as it does with unfiltered.  (I assume that 
one mode or the other makes VMS happy.  But I don't know about the other.)

The next thing that I would worry about is what specifically you're 
going to do with the MSA1000 on Linux.  Are you trying to boot from SAN? 
  Do you need persistent SCSI reservations?  (I don't know if the 
MSA1000 supports that.)

Finally, did the MSA1000 fix the problem that the older RA-4000 / 
RA-4100 had in that LUN IDs started at the upper end of the 16-bit 
address space?  I had to hack some FC HBA drivers in Linux to support 
that.  (Thankfully it was a simple check to see if the LUN ID was less 
than 256.)

> Is any software required on the Linux side beyond what is normally 
> on an Ubuntu installation?

I assume that you have at least two paths from the hosts to the storage. 
  As such, you'll probably want a multi-path implementation on Linux. 
DM-Multipath has worked well enough for me in the past.

> Also, my MSA1000 has the older MSA Fabric Switch 6 rather than the 
> newer MSA SAN Switch 2/8.  Are there any problems I should be aware 
> of with these?

Is the MSA Fabric Switch 6 limited to 1 Gbps Fibre Channel?

> If it cannot be shared, what would you recommend that can do it?

Given the age of the MSA1000 and speed that it runs at, I would think 
very seriously about something newer.  I would also consider building a 
new counterpart from Linux using Linux I/O / SCSI Targets.  I've happily 
used it as a SAN target multiple times.

My uncertanty comes form less familiarity with the MSA1000 (I have used 
RA-4x00 and MSA1500 more than MSA1000) and almost non-existent VMS 
interaction with SANs.



-- 
Grant. . . .
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