One of our beta testers recently came to us with an interesting backup-related question. We figured we would discuss it briefly here, and use it as a good jumping off point to talk about how to use the Filer as a backup system.
When this tester tried to run a backup, he was getting an out-of-space message from the cache. It turns out that his backup program was pre-allocating to see if it had enough space to write the data. The Filer responded that it did not have all that room immediately available.
And this was true. One of the major benefits of the Filer is that it stashes frequently accessed data in a local cache, then pushes the rest to the cloud so that your ever-growing store of barely-used files doesn’t sit on local, expensive discs. But that cache is relatively small. It certainly cannot fit an entire backup.
Instead of backup we recommended that our customer use network disk-to-disk copy to protect his primary storage. A tool like Robocopy is a good example of a tool that works well for this task. If Robocopy tries to copy data to a disk and that space becomes full, it simply tries again later, assuming you will make more space available.
This matches up nicely with the Filer, which automatically clears the cache on a regular basis. As the cache fills up, data steadily drains to the unlimited cloud. This is not instantaneous, though, which is why our customer was running into trouble. The disk looked small to his program because it was only seeing the cache, not the cloud behind it.
If you were to perform a large backup with Robocopy, the Filer would drain the data to the cloud at a steady rate, careful not to hog local bandwidth. Each time the Filer cleaned out the excess, Robocopy would drop in more files.
But what about being able to roll back unwanted changes to your data? How can you do that without backup?
Simple. The Filer has built in snapshot technology that makes backup unnecessary. The Filer’s snapshots will automatically capture any changes to your files. We don’t expect people to get rid of their backup programs entirely, especially during our beta phase. These programs aren’t the ideal source for the Filer, but using the appliance for backup certainly can be effective if done correctly.
If you’re having a problem with a similar issue, or have some related questions, let us know at feedback@nasuni.com.