Copy-on-write snapshots require more storage capacity than differencing disk snapshots, but how much more? Is there...
a way to calculate the difference?
The reason copy-on-write snapshots consume so much more storage space than differencing-disk snapshots is that copy-on-write snapshots retain copies of storage blocks, even after the data has been deleted or modified. This allows the snapshot software to revert a file or, in some cases, even an application to an earlier point in time without having to roll back the entire volume.
Unfortunately, there is no universal guideline for how much storage copy-on-write snapshots will require. The space required varies, depending on how rapidly your data changes and on your snapshot retention range.
You can get a feel for the rate of change by performing traditional differential backups and monitoring the size of those backups, but you must keep in mind that snapshots will typically consume more space than a differential backup will reflect. The reason for this is that a differential backup backs up your data as it exists at a point in time. The snapshot process is ongoing and in a 24-hour period, a snapshot will likely copy more data than a traditional differential backup would.
Dig Deeper on Backup and recovery software
Related Q&A from Brien Posey
Restoring VMware and Hyper-V virtual machines from a backup are similar processes, but there are a few important differences to keep in mind.continue reading
Expert Brien Posey explains how using a Bunch of Redundant Independent Clouds architecture can protect data, but not without three common hurdles.continue reading
Brien Posey dives into the complications users might run into with thinly provisioned VMware data stores and how to address them.continue reading
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.