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USB Flash Drives for Backup/Long-Term Storage?
cyberdigm is curious about this issue: "I am writing two books and have just recently gone through the trauma of having my hard drive flake out (physical damage to several sectors). Fortunately, while the OS instance was trashed, the file system is still intact, so I have been able to recover my files.Given that, I am now much more aware of the needed to regularly back up my files. I'd be interested in any opinions about the suitability of USB flash drives to help me solve this problem. The idea would be to store copies of all my files on a USB drive and back them up every day. I like that USB drives are generally fairly cheap. My concern is the long-term wisdom of this approach. Are there (practical) rewrite limits for USB flash drives? Is there a chance that the data would degrade on the drive over time? Other alternatives I am considering include external/USB hard drives. Of course, an overarching concern is that I'd rather not spend a lot of money."
Experiences in using flash memory for backups on PocketPC:
#1: Rewrite limits. Currently, flash memory has about a 1 million rewrite limit theoretically. In practice, though, I had a CompactFlash card (no real different technology from the USB drives other than interface to system) fail after about a year of daily backups.
#2: Time-to-destruction- I once left pictures of my honeymoon for nearly 6 months in my digital camera, also using flash memory. After 6 months, the files had a 50% corruption rate. So I wouldn't consider this a very long term storage solution- at least not without refresh.
Asside from those concerns, it's a very cool idea- especially if you kept the backup software on the key and increased your potential by using say, 7 keys (one for each day of the week) and kept the backups off site.
SJW: a person who perceives an injustice, and while correcting it, commits a greater injustice.
Software RAID on a bunch of different hard drives (preferably SCSI, but you can also use IDE/ATAPI/UDMA/USB) and automatic off-site (e.g. a remote ftp or scp) backup cron job should do the job.
Sincerely,
Pan Tarhei Hosé, PhD.
"Homo sum et cogito ergo odi profanum vulgus et libido."
which do you prefer?
why do people not realize that costs for the physical item are only part of a price tag?
comment directly in my journal
Almost all flash drives are made using cheaper & smaller NAND flash (rather then NOR flash which requires more transistors per bit of storage). This type of flash wears out much more easily then NOR flash.
If you decide to use these flash drives as a backup medium, you should definitely use some sort of encoding that allows for bit-corrections. Possibly some sort of Forward Error Correction. Or use a RAID parity/striping method.
Second, since we *are* just talking about text, it might be worth your while to use email. I've got a community network email account that I do this with - email them important info, they store up to 15 megs worth of data, where it will pretty much sit forever.
Third, little more expensive: last I checked, a 512MB USB disk drive costs about $70 CAD; you can buy a brand new low GB HD for about that much. Just run two HDs on your system, sync the data every night, and there you go. HDs don't tend to flake out as often as you think, and this way if one goes, you've still got an onsite copy. Then just buy another $70 HD and keep going.
Condemnant quod non intellegunt.
Back up your data off site on GmailFS.
Win32 Version
*nix version
The more media types and locations, the better, but concentrate on the small percentage of your data that you couldn't recover by just buying or downloading another copy. Concentrate on your own personal data, and the job will be much easier to manage.
The USB drive will be fine as one approach--use it daily--but don't leave it at that. It's a convenient medium, but you want it to be able to fail without hurting you much. If you combine it with other media, you can enjoy the convenience without exposing yourself to whatever risks there may be.
Then get yourself Web hosting from some reasonably good quality host and FTP your files to your own website. If you're not very technical, the Web host can tell you how. You don't need to learn how to build a website to FTP files. The more important the data is, and the harder to recreate, the more you need to have it on the website. If you can just get it up there, they will do your backup for you. This assumes that you don't have tens of gigabytes of personal data, which could be a mistaken assumption if you are talking about photography, for example, instead of writing.
From time to time, burn a CD-R of your files (or multiple DVDs if you have gigabytes of important personal stuff), make multiple copies, and stash them in different locations: with your parents, in a self-storage locker, or whatever. That's too much bother to do very often (if you include the offsite stash), but it's a good thing to do occasionally. Just to be sure, check and see if the CDs/DVDs you burn can be read in your parent's, friends, or kids' computers.
"Those who have never entered upon scientific pursuits know not a tithe of the poetry by which they are surrounded."
Any kind of backup solution is preferable to a single point of failure. USB Keys may not be the best solution out there, but it is certainly better than having only one copy on your hard drive. I would look at more than just USB keys, there are certainly plenty of options for copying and making backups of your data, from CD-Rs, and iPods, to zip disks, and external USB/Firewire hard drives.
While a USB key is certainly portable and convenient, it may also create another problem - easy theft of your work. How easy is it to lose a USB key, or have it stolen. And what happens if the finder claims your work as their own? If you did use a USB key, I would definately not keep it with you, but store it in a safe and secure location.
In that vein of thought, since you are working on a book, do you keep hard copy backups? I know it would be a pain to OCR all those pages back in if you lost everything, but it would be better than starting from scratch. If kept in a fire retardant safe, they would fare much better than digital media would.
I haven't lost my mind!
It is backed up on disk...somewhere...
My computer has 6 usb ports, get 6 usb flash drives and RAID 5 them. If one dies replace it ;)
These is my comments based on working in flash storage industry. There is an endurance limit to flash drives. The nand flash media are rated at about 100K erase/write cycles but in reality it can do more. There is additionally ECC correction to extend the life and preemptively recover with a sector goes bad. Once all the spare sectors go bad drive would likely prevent any further changes but still be readable. To give the most even wear and entend life, use a backup strategy where you erase all files and then rewrite or add incremently. Random write are the worse. Lastly flash failure decreases greatly with temperature so store at stable temperature.
When your house burns down, or floods, and your drives are underwater, including the backup drives?
Here is how I would probably do this.
First, check out RCS. You have one file, you want to keep a record of revisions.
Second, depending on how much I'd want to spend, I'd either back up to CDR once a week (keeping the old backup "off-site", say, on in my vehicle parked on the street, at work, etc) or else buy an online storage space for a few dollars a month.
A quick google search shows 50 MB for $3/month, which is a lot of plain text. If you are using some funky word processor format and/or images, half a gig is available for $10/month. It even supports rsync!
I have no idea how long the data will stay on a USB flash drive, or how many times you can write to one. I put my USB flash drive through the washer and dryer on accident. The drive contained my master's thesis in it. When I connected the drive to a computer, I discovered that not a single bit of data was corrupted. Doesn't that rock!
The only practical way to maintain integrity, given that data was stored offline (in fireproof safes) on mag tapes was to use a grandfather/father/son system of backups, with special tapes reserved for end-of-month or end-of-year processes.
I know we've come a long way since the days of batch-processing, but having a series of backups on separate media is way safer than relying on a single flash drive, CD-RW or whatever. The latter is bound to fail at the critical moment when it is most needed.
I run weekly backups on my home computers out to DVD-RWs which are overwritten in three-weekly cycles. More interim stuff on a day-to-day basis gets run out to USB flash drive or to CD-RW. Oh, and I set my backup scripts to alert me if there is even a hint of bad I/O an any media. Anything that is at all iffy is replaced immediately and the backup re-run.
I know this is a pedantic way of going about it, but I've rarely had any trouble with data loss as a result, while others seem to take it as a matter of course that they will lose their stuff when a drive fails.
I've had a USB flash drive fail completely after about two months of every-day (not heavy) usage. First the drive wouldn't allow me to overwrite a file, then it stopped mounting, and then it stopped being recognized as a valid device - all in rapid succession over 5 minutes.
This was with one of the Sandisk Mini Cruzer 256MB drives. I replaced it with another Cruzer (newer model), and after another three months it's mostly reliable, however I've had it become "unplugged" on its own a few times recently.