OpenVMS 8.4 (update 7), rx2800i2, p411 and StorageWorks d2700

[gmalacrida]

Hi all,

          we have an rx2800i2 Itanium box with OpenVMS update 7, a p411 controller card (RAID mode operated, no battery), connected to a d2700 external box.

Given that p411 has 2 connection and the p2700 has 2 I/O module, is a dual-path configuration

supported with all these stuff?

Thanks a lot in advance.

Giovanni

[Maurizio De Tommaso_ · Accepted solution]

You may link the P411 with the D2600/D2700 disk enclosures using only a "Single-domain” layout because the P411 SAS controller for the Integrity platform (Hp part number AM311A) doesn't support the “Battery and Backed Write Cache” option.

For this class of raid controllers, the “Dual-domain” support is activated by installing the SAAP (Smart Array Advanced Pack). Smart Array Advanced Pack (SAAP) is hosted on the Smart Array Controller hardware and can be enabled only on those controllers with a Battery Backed Write Cache (BBWC) module or a Flash Backed Write Cache (FBWC) module.

For instance, the Smart Array P812 ships standard with the features contained in the Smart Array Advanced Pack  (Hp Integrity part number AM312A – it includes 1Gb FBWC). This means the P812  + D2600/D2700  can be assembled in a "Dual-domain” layout. This configuration is fully supported starting form the OpenVMS I64 V8.4 Update 6.

Btw, few months ago HP has announced the release of SMART Array firmware 5.78b0 for P411 that enables support for Multi-Initiator to be used with HBA mode and OpenVMS I64 V8.4 Update 700.  This allows a new small cluster configuration of two HP Integrity rx2800 i2 servers with P411 interface cards sharing a DS2600 or DS2700 storage shelf.

SAS Terminology :

Single-domain configuration -  one cable path is created between the sas controller, the primary disk enclosure, and additional cascaded disk enclosures

Dual-domain configuration - two cable paths are created between the sas controller, the primary disk enclosure, and additional cascaded disk enclosures. Dual-domain SAS Configuration creates redundant pathways from servers to storage devices

Multi-Initiator - in the SAS arena refers to connecting multiple controllers to a common set of disk expansion drawers for the purpose of increasing availability

[fhsjvl]

Is it possible to elaborate on the exact configuration of SAAP?

I have tested a configuration but it did not work as I expected.

My configuration is:
- rx28000 i2 with OpenVMS I64 V8.4 including UPDATE V7 patch kit,
- iLO FW 1.53.02,
- System FW 1.80,
- p812 (AM312A) PCIe controller with FW 5.78 build 0, in first slot (full length) of primary I/O riser, card has cache and battery,
- AW526A = D2700 + 25x 500GB disks, has two I/O modules,
- first cable from Port 1e on p812 to port P1 of I/O module A on D2700,
- second cable from Port 2e on p812 to port P1 of I/O module B on D2700.
- Output of MSA$UTILS gives:
MSA> sho contr pkd
A default controller is not set. All matching controllers displayed

Adapter: _PKD0:
   P812             (c) HP                       PAGXQ0BRH1Q0LY Software 5.78
   Port Address: 50014380-182df170
Supported Redundancy Mode: Dual Domain.
         Dual Domain Mode: Dual Domain (Active-Standby with Failover).
Cache:
   912 megabyte read/write cache
   Cache is disabled and Cache is not configured.
   No unflushed data in cache.
Battery:
   Battery is fully charged.
Controller Mode:
   Controller is in RAID Mode.
MSA>

When I remove the first cable, I/O activity continues. When I remove the second cable as well, all I/O activity obviously stalls.

When I insert the first cable again, I/O remains dead and this remains so when I reconnect the second cable as well.

Similar tests with (old) SCSI connections and with FC connections are able to withstand such disaster scenario (removal of
both paths at the same moment). Why cannot my SAS configuration handle this? I use OpenVMS, so I want this to work fine.

[Maurizio De Tommaso_]

>>> Similar tests with (old) SCSI connections and with FC connections are able to withstand such disaster scenario (removal of both paths at the same moment).

Honestly, i believe that your scenario was never supported by the OpenVMS architecture.

If necessary, please contact your local Hp support and ask them about this point.

it is my opinion that OpenVMS Shadowing (HBVS) + two SAS disk shelfs + two P812 SAS controllers (properly configured) are the correct design to survive in case of loss of both SAS cables/paths linked to the same "storage box".

The SAS "Dual-domain" design can tolerate exclusively the loss of one cable/path.

To test the SAS "Dual-domain" functionality , the correct steps are  :

(your configuration = one P812 + one D2700 with two I/O modules + two SAS cables)

1. disconnect one SAS cable; verify the correct access to volumes from OpenVMS side.
2. reconnect the SAS cable, wait 10 seconds and disconnect the other one; verify the correct access to volumes from OpenVMS side.
3. reconnect the SAS cable

SAAP functionality is standard on the HP Smart Array P812 controller, as confirmed by the command output "msa$util show controller PKD"  :

Supported Redundancy Mode: Dual Domain.
         Dual Domain Mode: Dual Domain (Active-Standby with Failover).

You have to take a look at the P812 controller cache setting :

Cache:
   912 megabyte read/write cache
   Cache is disabled and Cache is not configured.
   No unflushed data in cache.
Battery:
   Battery is fully charged.

Is this the desired configuration ? Without the appropriate read/write cache configuration, the performance of the P812 will be very poor. 

[fhsjvl]

Of course, "cache disabled" is not desired configuration.

How to enable it? And why is it not enabled automatically when present?

PS: I agree that two SAS PCIe cards are needed for correct "dual domain" operation.