Might Flash Memory be a Viable Backup Medium?

General Books asks: "Rather than fuss over mechanical failures and damaged media, why not use flash memory for backups? We maintain about 100 servers distributed to customers' sites. Each night we copy a backup of critical data (generally less than 128MB) to removable media in case the hard drive fails. We have experienced high failure rates with CDRWs and so now I am considering some sort of flash memory like a USB key drive. They are solid-state and you can get a 128MB device for $20. They seem ideal to me, but I can't find solid evidence. One question is how would they endure a lightning strike (perhaps not as good as an optical medium)? Admittedly, there is a wide variety of CDRW drives and media but don't they all seem risky compared to a solid-state device? More info about my circumstances: We have no network for backups. A second hard disk is not viable because it could not be rotated offsite. Tape drives are relatively expensive and overkill for our volume of data."

Comments

How about CD-R ?

[orkysoft]

You mentioned that CD-RWs weren't all that good, and I have the same experience, but why not try normal CD-R discs? They're cheap and pretty reliable. You can even make multiple backup copies if you want, or a multi-session disc to store several backups on one CD to cut costs.

I've had no luck with Flash Media

[xanderwilson]

I cross my fingers (no, not literally) every time I've inserted a piece of Flash Media into my camera, PDA, or USB drive. I find that about one in every 20 times the disk comes up empty. I take good care of them (three different media types), but I don't find them reliable at all. I'd sooner use CD-Rs (though now I might start backing those up every 2 years on new CD-Rs.

Alex.

Re:I've had no luck with Flash Media

[amlai]

On Windows machines you have to "eject"(stop the device totally sometimes to get the files copied to the device. I have experienced similar problems and a clean stop before removal will do the trick.

Re:I've had no luck with Flash Media

[JediTrainer]

I've had a similar problem too. Here's what you do: Go into your control panel. Find the device (under System or whatever). Go to properties. There should be a checkbox there for 'removable'. Make sure it's checked.

Er, wait.

[dasunt]

Before you give up on CD-R/CD-RWs, try this:

• Make sure you have a decent CD drive. If you have a first-generation CD-R drive, replace it. Lite-on is cheap, but seems to do well in reviews.
• Burn at the lowest possible speed for a better burn.
• Verify DMA settings for each device.
• For an IDE burner and an IDE hard drive, keep the hard drive on a separate channel from the burner. For example, set up the hard drive as primary master, and the CD drive as secondary master.
• Keep the burned CDs in a cool, dark place. Use a jeweled case for each to prevent scratches.

I don't see any reason why USB flash media wouldn't work for backups if the OS supports it. The only problem is that USB flash media is more expensive then CD-Rs. $20 will buy you enough CD's for a monthly 'archive' (12 CDs/1 per month), plus a weekly backup/incremental daily backup (4 per month), even if you don't reuse the weekly backup media (personally, with the cost per CD, I wouldn't). However, to implement such a system with USB flash drives (assuming $20/drive), would cost $320 dollars.

I love my USB flash drive, but its not cost effective for backups.

Limited writes

[Kris_J]

Flash RAM has quite a limited number of writes. This can cause problems if you're writing large numbers of small files to flash RAM as it can cause a huge number of writes to the FAT area of the device. This may have been solved with different file systems, but I recall reading a story of one person who was getting failures. CD-RW discs avoid this problem by preparing the files and writing them in a single batch.

Is the "generally less than 128MB" before or after compression? A nice compression package like 7-zip might get the files down to a size that can be emailed off-site each night.

Flash memory and remote backup

[Halvard]

Rather than fuss over mechanical failures and damaged media, why not use flash memory for backups? We maintain about 100 servers distributed to customers' sites. Each night we copy a backup of critical data (generally less than 128MB) to removable media in case the hard drive fails.

Both of these would be my recommendation. I use flash media to boot firewalls, routers and embedded servers that run from RAM drives (nearing 100 deployed at customer sites and in our network). But I automount a partion on CF modules for logs. Flash memory is very reliable; it's rated at about 100,000 destructive writes. Read that as wiping it out, reformating it, not as I wrote to /var/log/messages for a week and the media toasted because somebody's machine caused the firewall to log crap every 2 seconds for a week. If it wasn't reliable, Cisco wouldn't use it for non-volatile storage (neither would I).

The way we handle server backups is for servers to backup via a script to a tar.gz file over a private T-1 for servers. Granted, this amounts to a lot of GB for us but if you use something like rdiff-backup or a more simple script that backups up your files across the net through an SSH tunnel, you should be in pretty good shape. CDRWs are a poor choice if you can't or won't rotate media routinely. Especially since their lifespan for writes is low. You or your customer will have to rotate if you use CDRWs.

Google

[Molina the Bofh]

The best way to know the answer (as always) is RTFMing.

You can read the Compact Flash FAQ

A quick google search returned these links, that may be interesting to you

IDE to Compact Flash Adapter

Flash Storage Solutions

Read all this thread if you will be storing sensitive information

How Compact Flash can keep your data safe?

This guy has an opinon different from mine. He says that, all of a sudden, he lost hundreds of picture. Well, I've been working with Compact Flash for more than one year, now, and the ONLY time I gost corrupted data was when I took the card off the camera while it was writing. Then the camera could not read any picture. They seemed to be lost. But later I put that CF in my CF reader, and ran a chkdsk. It found lost chains, that I saved as files. And recovered ALL pictures except for the bottom half of the one it was writing at the very moment when I removed the CF. It probably corrupted the FAT (same way as hard disks, when the computer is not properly shut down).

And I do think CF is more reliable than Microdrive.