pdsmicro
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snap shot space
I have seen many storage devices require 25% or somekind of % space for snapshot.
i am wondering how it is possible when i create 10GB VD and he snapshot space only 2.5GB.
is not it suppose to be 1:1ratio?
i am wondering how it is possible when i create 10GB VD and he snapshot space only 2.5GB.
is not it suppose to be 1:1ratio?
A Clone would be 1:1 space but a Snapshot only holds the blocks changed, thats why they normally only take up a small proportion of the volume they are a snapshot of. An old rule of thumb is that 80% of writes goto 20% of the disk.
Snapshots can either be Copy-on-write or Redirect-on-write, COW means the original data is stored in the snapshot, ROW means the new data is stored in the snapshot
Snapshots can either be Copy-on-write or Redirect-on-write, COW means the original data is stored in the snapshot, ROW means the new data is stored in the snapshot
It depends on the hardware/software. Are you talking about consumer or enterprise grade storage? What exactly are you looking to accomplish and does it involve specific application or just file server data?
ASKER
This is an enterprise storage devices.
I read dell equalllogic tech notes and it says that we allocate 25% of volume space for snapshot.
NetApp says % for snapshoto.
Jetstore says 2:1 for snap shot.
When we create 1TB space for volume the we give 25GB for snapshot.
how that 1TB data is being converted to 250GB?
I read dell equalllogic tech notes and it says that we allocate 25% of volume space for snapshot.
NetApp says % for snapshoto.
Jetstore says 2:1 for snap shot.
When we create 1TB space for volume the we give 25GB for snapshot.
how that 1TB data is being converted to 250GB?
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ASKER
thank you
can you explain what this is about??