One DS2300 Disk System with two rp5470 - MCServiceGuard Possible ?

[Wolfgang Niefert]

Hi,

we have one DS2300 Disk System and two rp5470 and would like to create a MC ServiceGuard Configuration.

- 2x rp5470
-- includes A6828A PCI Ultra160 SCSI-Adapter each and
- 1x DS2300 with 2nd Bus Control Card


Is it possible to connect the two Hosts two one Disk System in Full Bus Mode ?

Is it possible to create a MC ServiceGuard Configuration with one DS2300 ?

Thanks

[Steven E. Protter]

If the DS2300 has input for multiple scsi inputs and the device itself is compatible with Service Guard, the answer is yes.

SG requires a shared disk. This disk is mountable by one node or the other, not the same time.

SEP

[Jeff Schussele]

Hi Wolfgang,

Yes - but I would have *two* PCI SCSI HBAs in each host connected to *two* ports on the DS2300. You'll have to change the HBA SCSI IDs to avoid ID conflict.
If you don't you'll have a single point of failure - the HBA.
And yes - as far as I know - the DS2300, with 2 bus controllers is supported by MC/SG.
But - again - two DS2300s are suggested because the DS2300 itself would be the SPOF.

Rgds,
Jeff

[Wolfgang Niefert]

Hi,

thanks for the response.


We currently have two rp5470s where each rp5470 has one A6828A PCI Ultra160 SCSI-Adapter installed.

The DS2300 is a Dual-Controller Configuration.

I thought we connect the two Hosts to the DS2300 System in Full Bus Mode.

Are you saying we need two A6828A PCI Ultra160 SCSI-Adapters in each Server ?


Thanks

[Jeff Schussele]

Well - it's more a matter of what you can get away with. What you *need* is 2 HBAs per host *and* 2 DS2300 units.
What you can "get away with" is 1 HBA per host & 1 DS2300. But you'll now have 3 SPOFs - each HBA in the hosts & the single DS2300.
Clustering is all about redundancy - the capability to survive equipment failure & keep on running.
I sure hope you intend to mirror the disks in that DS2300 or you can add another SPOF for *every* unmirrored disk drive in there as well.

My 2 cents,
Jeff

[Wolfgang Niefert]

Hi,

thanks for the response.

We know the optimal Configuration is all about redundancy.

However we need to look at the minimal technically feasable configuration.

We are planning to mirror the Disks using HP MirrorDisk. There are 4 Disks planned for initial Setup.

We may need to setup a MCSG Volume Group and also configure 2 additional Volume Groups for Oracle Files.


Thanks

[Stephen Doud]

No Inline Terminator SCSI cables are supported for Ultra160 or Ultra320 SCSI, so this limits the online repairability of shared Ultra160 and Ultra320 SCSI buses. The DS2300 offers online repairability in certain configurations (see below). No V-cables exist for Ultra160 or Ultra320 SCSI, which limits the number of nodes that can be connected in a shared Ultra160 or Ultra320 SCSI bus to two. The DS2300 can allow up to 4 nodes to be connected in a shared Ultra160 bus configuration, however if more than 2 nodes are connected to a DS2300 it will prevent online repairability for that shared SCSI bus.
The DS2300 disk enclosure can operate at Ultra2 and Ultra160 SCSI speeds. ILT (inline terminated) cables are not supported with it, but it's design allows similar functionality to ILT cables in certain configurations. The DS2300 has 2 isolated BCC's, each with 2 SCSI connectors. For High Availability configurations, each host is connected to a different BCC, and the remaining connector on each BCC must have a SCSI terminator on it. The DS2300 must be configured in "Full Bus mode", so that all nodes can see the same disks. This is still a Multiple Initiator bus, so the HBAs in each host must have a unique SCSI ID, and they must be the highest priority SCSI IDs (7 and 6). Since there are only 16 possible SCSI IDs, and the DS2300 enclosure holds 14 disk modules (each using one SCSI ID) and the enclosure services processor uses one SCSI ID, one disk module must be removed from the enclosure in order to allow two Host Bus Adapters to be connected to it. When a SCSI cable is disconnected from either BCC connector on the DS2300, the isolation provided by the BCC will allow the host connected to the other BCC to continue to access the DS2300 without interuption. To allow applications to continue to run after the failure of a Host Bus Adapter, it is required to have two DS2300's mirrored together, each connected to a separate SCSI HBA. This configuration is supported for Ultra2 SCSI and Ultra160 SCSI bus speeds.