Rooey wrote:
When using a 3par snapshot, I'm assuming the whole LUN is snapshot to the COPY CPG? As opposed to a VMware snapshot where an individual snapshot is taken per VM and stored with the VM.
The "whole" lun is not copied to the CopyCPG, just the deltas or changes made since the snapshot was created. If the original volume is pretty static, with little to no changes... the cost in megabytes of the snapshot will be quite small, if its a drive with a high change rate, such as an oracle redo log, then the snapshot will probably take up as much copycpg space as the source volume uses within a few hours. The snapshot uses a "copy on first write" method to preserve the data. When a snapshot is created, it starts basically as copy of the original volume's table of contents, with read only pointers back to the original blocks of data. If the original volume needs to edit a data that has a snapshot pointer back to it... it copies that block down to the CopyCPG and then lets the original volume change that block as much as it wants to. If a host has a read/write snapshot mounted up and wants to make a change to a block that is a pointer to original volume, then the pointer is dropped and replaced with a real block allocated into the CopyCPG.
Quote:
If I want to recover a VM from this LUN level snapshot whats the process? Can I restore an individual VM from the LUN Level snapshot back to its original LUN where other VMs are probably still running, without affecting them?
In addition to what was already said, HP makes a special application called Recovery Manager for VMware that will manage and automate most of your VMware related snaps and recoveries. I've never used it, but I am sure someone on these forums could shares some opinions on whether or not its a solid solution or suggest alternatives.
Quote:
Is it possible I could lose my base LUN ever, maybe corruption, accidental delete, malicious delete? If so, does that render my snapshots useless as its taken from the base?
Depends on what the corruption is... if you use Raid0 cpgs and your lose a drive... or by some malicious admin, lose your CPG or yank several magazines of drives from the array... snapshots are not a DR solution unless you are also using Remote Copy (which basically takes a snap and replicates the snap to another 3PAR). If your host somehow manages to corrupt the VMFS datastore, or SQL datafile, etc... "logical corruption" then yes a snapshot would be an ideal method of quickly restoring.
Quote:
Does my snapshot LUN need to be atleast the same size as the LUN I want to snapshot
As previously stated, you can't edit the size of snapshot... it inherits it size from the source... HOWEVER, if you are using snapshot copies for building duplicate instances, such as a snapshot of a production database mounted up on a dev host... you CAN promote a snapshot to regular volume, then grow the LUN as needed. Cloning is also an option, it uses a snapshot to copy a volume at an exact point in time, then copies the snapshot into a stand alone volume. The clone is immediately available for use even before the copy is finished due to the snapshot.
Quote:
Can you point me to some easy reading/videos/training material that might show me more about what I am trying learn?
I don't know about "easy", but the 3PAR Storserv Concepts Guide is a good start to a 3PAR overview of all its features.
http://h20566.www2.hpe.com/hpsc/doc/pub ... n-us&cc=us