3PAR Active Active Cluster

[TTAdmin]

I have a question about Hp 3par peer persistence,  Can this feature writes data in a  same time with active active in both storage ?  I mean each  host can read and write actively on same lun in both storage.

When I check from Hpe website, What I see, In peer persistence documentations,  Two storages are working like active and passive mode, because it looks one of them is primary and the other is secondary.

I need to know, If it is not working active active cluster. I will  push customer to continue HP XP7 or ıf you recommend other solutions to me, please let me know.

[ZARA1]

Hello

Hp peer persistence technology is working little bit different,  It is working one storage primary and other one is secondary. This is not real active active cluster.

In that architecture one storage is primary and all data read and writes transactions directly come primary than it is copying to secondary.  In real active active clusters,  There is no primay and secondary.

 İn real active active storage cluster scenario both storages are working actively and each writes and reads requests from hosts to storages in same time. There is no backround replication.

 For that reason, If you are competing other vendors with active active storage cluster, your choice must be HP XP7. 3par is good product and but ıt does not have real active active storage cluster option.

If you have any question about, please let me know

Best Regards,

Hpe Consultant

Zalina Ramanova

[victor-c]

Hi,

Could you explain more for what task you need Active-Active? What scenario for use?

Best regards,

[Sheldon Smith]

Peer Persistence is layered on top of (synchronous) Remote Copy. Logically, data is written to both systems at the same time. The host writes to the primary system, the primary replicates the write to the secondary. The host write completes. Reading is done from the local (primary) system for performance.
Again: what problem are you trying to solve?

[Vijay_Agrawal]

We have 2 openstack clusters in 2 sites, planned to be in active-active mode (both serving requests), each having their own 3PAR storage backend with cinder.

VMs in both clusters should be able to write to the storage and the storage needs to be in-sync in both sites

Having 2 3PAR arrays serves as DR mechanism too..

It appears above use-case cannot be met since 3PAR is active-passive, right?

[Sheldon Smith]

A 3PAR system is always active-active; all controller nodes share the IO load. A pair of 3PAR systems running Remote Copy are active-passive: One system does the IO and sends written data to the other.

You have 2 openstack clusters, one at each site?
Each cluster has its own storage, so each cluster would read locally from its primary system and copies of the writes would be replicated to the other side's secondary system. Site A's cluster, controlling one set of volumes, would have writes going to storage at Site B. Site B's cluster, controlling a second set of volumes, would have writes going to storage at Site A.

If both clusters share the same storage (How do two separate clusters coordinate their IO without corrupting the data?) then the 'stretched' cluster would need to do host-based mirroring instead of having the 3PAR systems use Remote Copy.

[victor-c]

How I understand, it is not correct question. This is not regarding controllers, this is regarding LUNs

How Sheldon written below: "A 3PAR system is always active-active; all controller nodes share the IO load. A pair of 3PAR systems running Remote Copy are active-passive: One system does the IO and sends written data to the other."

With other words, if virtual volume (VV) from 1st storage is copied to 2nd using Remote Copy, for primary storage this VV is Read-Write and on secondary storage is just Read-Only.

If you need distributed cluster, you need distributed access network with small latency (or FiberChannel or iSCSI). I have few implementations for VmWare cluster (I have FiberChannel on Dark Fiber link).