Snapshot size

[tom__w]

I have a production NAS box that I have setup to snapshot every hour. I then replicate those snapshots to a DR NAS box. The volume is approximately 800 GiB in size with 4.1 TiB of free space.

My snapshots are between 500 Meg and 1.5 GiB .. every hour.

My DR NAS is in the same server room as my production box so its really more of a pseudo DR. I want to move the DR off site but I am concerned about how large the snapshots are and how long it would take to transmit that much data over the internet.

I know that the snapshot is only that of the changed data .. and I know that this can vary wildly based on the data being accessed. But do the snapshot sizes above make sense? I primarily use the NAS box as a datastore for VMs. That is, I am running approximately 6 VMs.

Thanks from a newbie (but learning).

 

[ser_rhaegar]

For VMs? Depends on what they're doing.

I'd probably consider a larger snapshot window if your WAN can't transfer that much per hour. Otherwise I wouldn't worry too much about the size.

 

[tom__w]

If I opened up the window to 2 hours (for example), wouldn't the snapshot size be twice as large? (or close to it)

 

[ser_rhaegar]

Depends on what changes. The same bits could be changing every hour, making a larger window smaller overall.

Do you need to be able to restore losing only an hour of work or can it be a days work? What are the requirements per your DR plan?