Snapshots

Last updated: September 13th 2019

Performance

Snapshots of your Webdock server are true snapshots in the sense that they capture an exact disk image at the time of snapshotting. Any running processes or contents in RAM are not captured however, and when you restore or provision a server from a snapshot, it will act as it was just rebooted.

Snapshots are not limited in size and will be of your entire server disk size. This means a server using a lot of disk space will take longer to snapshot. On our SSD servers we operate with an average of 200Mb/second snapshot efficiency. This means that a 60GB Webdock server at full capacity should take about 5 minutes. 

Once snapshot, the snapshot needs to be synched from a secondary local drive to our remote storage backend so it's ready to be picked up for provisioning or restoration. This process usually operates at about 200Mb/second,  but speeds may vary depending on network conditions and other factors. You can get an indication of how long a snapshot will take in the Webdock backend panel for snapshots, as there we list the last recorded snapshot duration as seen by our nightly snapshot job

Snapshots are not incremental

We do not do any incremental snapshotting. We always make 100% complete standalone duplicates of your entire server. We Keep It Simple as storage is cheap and plentiful these days. This makes snapshots extremely portable and keeps complexity to a minimum. If you have ever had to deal with a backup chain gone wrong, you might appreciate our philosophy.

Snapshots are nightly

Depending on the server location, we always schedule our daily and weekly snapshots to run at night between the hours of 01.00 and 05.00 in the local timezone. This is so we have as little impact on production websites as possible. As mentioned above, snapshotting means that we are reading from disk at full throttle and streaming the data to another drive and then to a remote storage backend. CPU impact is held to a minimum and will never reach more than 30-40% of total server CPU seconds (it is this high as we multithread-gzip the data as well). 

The server will experience higher than usual I/O load which might in theory impact your server performance. Usually a nightly snapshot of all servers on a host takes no more than 1-2 hours.

How we estimate snapshot time

Once we have backed up your system once, you will be able to see an estimated snapshot time on the Snapshots page for a server.  This estimate is based on how long it actually took for us to take the nightly automated snapshot.

This estimate can vary from day to day based on whether you have added or deleted data from your server, disk I/O conditions at the time of snapshotting and as we include the time taken to synch the snapshot to our remote storage backend it will also depend on network conditions at the time. 

If you create a snapshot yourself you can expect to see divergence from this estimate, but it should give you a fair idea of how long a snapshot should take. Sometimes snapshotting will be faster, sometimes it will be slower due to the factors mentioned above.