#1621 cpsv: add support for 'cloud resilience' feature

[Pham Hoang Nhat]

This enhance supports to preseve checkpoint replicas in case both SCs down (headless state) and recover replicas in case one of SCs up again. If both SCs goes down, checkpoint replicas on surviving nodes still remain. When a SC is available again, surviving replicas are automatically registered to the SC checkpoint database. Content in surviving replicas are intact and synchronized to new replicas. When no SC is available, client API calls changing checkpoint configuration which requires SC communication, are rejected.
Client API calls reading and writing existing checkpoint replicas still work.

Limitation:
The CKPT service doesn’t support recovering checkpoints in following cases:
• The checkpoint which is unlinked before headless.
• The non-collocated checkpoint has active replica locating on SC.
• The non-collocated checkpoint has active replica locating on a PL and this PL restarts during headless.
In these cases, the checkpoint replica is destroyed. The fault code SA_AIS_ERR_BAD_HANDLE is returned when the client accesses the checkpoint. The client must re-open the checkpoint.
While in headless condition, accessing checkpoint replicas doesn’t working if the node which hosts the active replica goes down. It will back working when a SC available again.

[A V Mahesh (AVM)]

Is this extended part of cpsv: Support preserving and recovering checkpoint replicas during headless state Ticket [#1621] ?

[Pham Hoang Nhat]

"cpsv: Support preserving and recovering checkpoint replicas during headless state" is a patch for the ticket #1621

[A V Mahesh (AVM)]

changeset: 7319:6ddbce46d3e6
tag: tip
user: Nhat Pham nhat.pham@dektech.com.au
date: Fri Mar 11 09:07:35 2016 +0530
summary: cpsv: Support preserving and recovering checkpoint replicas during headless state [#1621]

[A V Mahesh (AVM)]

changeset: 7324:0cc809a7b3db
tag: tip
user: Nhat Pham nhat.pham@dektech.com.au
date: Mon Mar 14 08:59:43 2016 +0530
summary: cpsv: README.HEADLESS for cpsv service functionality [#1621]