Wow … I now have to opportunity to work with HP EVA. So I need to catch up on how this thing works in the coming days … so far, I am learning that it supports 3 types of replicated data.
So what’s the deal with these replicated data type…
Snaphots are dependent point-in-time copy of a virtual disk. This is usually used when you need a temporary copy of the data for cutting to tape. It allocates a space to contain the metadata and pointers to the original source and copies the original content only when it is overwritten on the source. Hence it consumes the least amount of space. If you need data intensive access, this will affect the performance of the original source as it shares the data with this snapshot copy.
Snapclones are independent point in time copy of the virtual disk. It is a byte by byte copy of the original. Intensive data access to this copy with not impact performance of the original source disk so this makes it good for data mining or data warehousing and doing some intensive number crunching. Software development teams can make a snapclone copy of the live data and do testing without affecting the production users.
Mirrorclones are linked copy of the virtual disk. It is much link a snapclone but it can resynch with the source. Not a one shot deal. It have different states which can be modified by commands to the system. When it is first create, it is said to be in a “Synchronized” state. Any changes to the source disk is also replicated to the mirrorclone. When you need a point in time copy like a snapclone, a mirrorclone can be “fractured” from its source. At this state, any changes to data on the original will no longer be replicated to the mirroclone. You can also resynch the mirrorclone from its source. Doing so will put it in to “Synch in progress” state and once complete, it will return tobe in a “Synchronized” state. You can restore from a mirrorclone to your original source. This command will put the disk into “Restore in progress” state until it becomes fully synchronized. Mirrorclones can also be dettached which makes it a normal virtual disk and ceases to be a mirrorclone.
I’ll share with you as I learn more about this beauty in the coming days …