One of the great new features in NetWorker 8.1 is virtual synthetic fulls.
You may think the term ‘virtual synthetic’ sounds a bit meta, but it’s quite accurate when it refers to synthetic fulls being virtually constructed on Data Domain devices.
You see, while synthetic fulls were introduced in NetWorker 8.0, they had a catch when running on Data Domain Boost devices – the data would still be rehydrated. That is, NetWorker would read through the full and all incremental backups referenced and rehydrate the data to construct a new full backup, saving that full on the Data Domain (with inline deduplication obviously happening again).
There’s nothing incorrect about that process – it is, after all, exactly what happens on standard AFTD devices. But it’s not the most efficient way of going about it.
That’s where NetWorker 8.1 and virtual synthetic fulls come into play. In this scenario, NetWorker instructs the Data Domain to create a new full backup via Boost. For the Data Domain, this consists of giving NetWorker back the appropriate reference data for the saveset after (mostly) jiggling pointers and updating its own back-end file data.
The net result is speed. Virtual synthetic fulls are fast on Data Domain because there’s very little data being rehydrated – deduplicated data is just being adjusted. You can see how fast this is because NetWorker reports the operation as if it were happening as realtime data:
That’s 1860236 KB/s being reported … 1816 MB/s throughput, and that’s just what I managed to capture – it was a smaller saveset, and it was pumping along. But the client itself in question was connected over 802.11n. There’s no way it could be running at that speed over the ether – the speed was coming from the operation being performed on the Data Domain itself – and that Data Domain had a bunch of other activities happening at the same time.
Synthetic fulls are useful under NetWorker 8.0, but in 8.1 and combined with Data Domain, they can be a complete game changer to your backup windows.