Are server backups to flash drives feasible?

Question

If I were to use a flash storage device on a server, a portable one specifically, and backups written to it periodically every 5 hours or so, would there be much wear to the flash drive to the point of depending on it as a reliable fallback to data recovery? Since there wouldn't be a lot of writing involved all the time, the flash drive's lifespan isn't reduced that significantly right?

Or maybe somehow in addition, get the filesystem driver to use fresh blocks for all allocations instead of old ones to maximize flash cell lifespan?

Reason I want to do this is to avoid using up bandwidth for network backups, and there aren't any other local servers to perform such backups without overall internet latency. And that flash storage devices are cheap and easy to obtain.

NOTE: I'm no hired IT, I have a low budget and run a home server if that's any specific. Also I'm looking to backup are web directories and SQLServer DBs.

Answer 1

I've had some experience with failed flash drivers, and usually the main problem was the controller, not the flash chip itself, but I still wouldn't use it for main backup.

Flash chips usually have limited write cycles, so you can overwrite each 'sector' only times (~10.000). If you write one backup per day, that's a long, long time. If you write logs there, or copy something every couple of seconds (or have a /tmp dir there), that's not going to last long. Most newer controllers have wear leveling, and change the location of blocks (they have a couple of them extra), so the wear is distributed across the whole flash chip.

Using it as an extra backup, with sequential writes (no often overwriting), might be a good idea, but i woul definitely keep my "main" backups somewhere safe (hdd raid, or tape, or both).

Answer 2

I probably wouldn't rely on flash drives for server backups. I just wouldn't trust the reliability.

If you have no network storage then you could purchase USB hard drives for the backup. We use external USB hard drives for backup drives. We copy to a machine that has a large internal drive and then use a robocopy script to replicate to external USB drives that are swapped out each day and rotated. I have also done this for clients with drives directly attached to server.

Answer 3

If your client cannot afford more than $70 to backup data, look for a better paying gig.

That being said, the other answer is valid, they are unreliable and too small. Why not take a look at software like CrashPlan (free) and do versioned synchronization from one machine to another that that has a large disk just for backups from other machines. This will only help you with data unfortunately, not system state operating system recovery.

Answer 4

What's interesting with this question is the shoestring budget. This makes it less off a professional server question. However there are some simple tests that can be applied to this kind of question regardless of scale of economy. (This is after all a site for giving / getting answers not comparing the size of each other's paycheck).

To directly answer your question. No SD will most likely be fine. Oddly a backup that completely overwrites the card is one of the least intensive uses of one. Its not the number of bytes you write, but the number of times you change an individual byte) What really kills them is letting a program use them for temp space (as some programs will automatically do the moment you edit a file directly on the flash drive). Remember that backing up every 5 hours is only changing each sector every 5 hours. It will wear, but after a long time.

Is this advisable? That's a simple question to answer: What is your data worth to you / your company / your client?

Think of a backup like an insurance policy. On the assumption you're going to replace this backup solution completely in 2 years. $70 is cheap for protecting the average home business data for two years. The price of a sizable SD card these days is almost as cheap as many of us pay for a coffee. So only consider using an SD card if loosing that server's data would be an annoyance (couple of weeks work wasted) and nothing more.

Make sure your backup solution is verifying each backup (SD wear should be detectable if you also store check-sums of the files) and swap between two or more so that if one fails you're not more a day or two behind.

Finally consider using a good quality flash card. Remember that photographers fill up and clear down these daily. Your suggestion of doing so once in 5 hours isn't that far removed from what the good quality ones are designed for.