Go Back   Steve's Digicams Forums > Digicam Help > General Discussion

Reply
 
Thread Tools Search this Thread
Old Dec 10, 2007, 12:46 PM   #11
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,571
Default

I would like to make a distinction here, if I may.

There's "backing up" and then there's "archiving".

Backing up is for documents that you are working on, so that if the unforeseen happens (most often, you screw up; ocassionaly, software or hardware screws up), you can restore from the backup.

Archiving is for documents you want to preserve in their current state for posterity.

For archiving, magnetic media is a bad idea. Optical media are a much better choice, but even optical media will eventually degrade to the point where it is no longer useable. So, if you choose to use CDs, DVDs or whatever, for archiving, you need to recreate the archive periodically. That is, you need to restore the archived documents periodically, and use them to create a new archive.
TCav is offline   Reply With Quote
Old Dec 10, 2007, 4:59 PM   #12
Senior Member
 
Join Date: Jul 2005
Posts: 200
Default

One thing I find important is to design a folder structure for the inititial hard drive storage that makes it much easier to perform backups. If someone stored all the data in one folder, the whole folder needs to be backed up every time. But if for example, a folder structure based on days, weeks, months or years depending on volume is used, you only have to back up the "historical" folders once. andbackup ofthe current folder can be automated andregular. I use multiple drives on networked computers + DVDs for monthly backups, and an automated backup to a flash drive for daily backups of the current folder. Although it is tedious, I do a monthly restore from DVDs from a photoshop album backup of all photos on one PC to the same program on another PC, and did find once that the the backup was corrupted.

You have to decide how important data, i.e., your pictures are to you, and then how much time and money you are prepared to spend to keep them safe. If the backup processes are not automated, you have to be very disciplined to make sure they are carried out routinely. Hard disks seem to be more reliable, but I have suffered several times over the last 20 years with periodic failures, so I am a little paranoid about backup.
1eyedeer is offline   Reply With Quote
Old Dec 10, 2007, 9:19 PM   #13
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,571
Default

1eyedeer wrote:
Quote:
...I am a little paranoid about backup.
It's not paranoia. Time really is out to get us. :-)



TCav is offline   Reply With Quote
Old Dec 10, 2007, 10:34 PM   #14
Member
 
Join Date: Aug 2004
Posts: 48
Default

A while back most corporations used a tape back-up system. Although slow because its a continuous stream, it did provide a medium that had a long time duration.

Does a tape system still seem to provide this longevity?

Since we are looking for a long time archieval, maybe the apspect of a quick restore does no longer matter. The long term saving does.

What do you guys think?

Gritty
Gritty is offline   Reply With Quote
Old Dec 11, 2007, 3:20 AM   #15
Senior Member
 
Join Date: Jul 2005
Posts: 200
Default

I used to sell multi-user Unix systems to hospitals and medical records were backed up to tape with a rotation schedule. At that time, Dat tapes with jukebox automatic changers had sufficient capacity but I don't know if this is still the case. Some of our users insisted on Microfiche as the only safe long term media, and you only need a simple microfiche reader - back to film!
1eyedeer is offline   Reply With Quote
Old Dec 11, 2007, 8:38 AM   #16
Senior Member
 
VTphotog's Avatar
 
Join Date: Mar 2005
Location: Extreme Northeastern Vermont, USA
Posts: 4,229
Default

Magnetic tape has its place, but is not any more permanent than any of the other media being discussed. Even if stored under ideal conditions, it suffers from print-through and deterioration. For regular back-up use, yes, but it isn't an archival medium.

I anticipate that the need will eventually be filled by someone coming up with a (relatively) inexpensive method to press DVDs. This is permanent, but the tooling costs would be prohibitive, unless you are a government agency.

brian
VTphotog is offline   Reply With Quote
Old Dec 11, 2007, 8:43 AM   #17
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,571
Default

Gritty wrote:
Quote:
A while back most corporations used a tape back-up system. Although slow because its a continuous stream, it did provide a medium that had a long time duration.

Does a tape system still seem to provide this longevity?

Since we are looking for a long time archieval, maybe the apspect of a quick restore does no longer matter. The long term saving does.

What do you guys think?

Gritty
Tape is an attractive backup medium, but not an attractive archival medium.

Tapes are magnetic media, just like floppy disks. As with any magnetic medium, the magnetic signal fades over time, so at some point, the data can not be reliably retrieved. But in addition to the problem of fading magnetic signals, tapes are a flexible medium, which means that each time you use it, the adheasive that binds the magnetic particles to the tape are stressed, and some of those magnetic particles flake off the tape. Each and every time you use a tape, it is less and less likely to work.

So, as an archival medium, tape is not a good choice. Some organizations do use tapes for archiving, but the way they use it is to make a complete archive and store the tape in a fire proof safe off-site, and do the same thing every day (or every week, or every month, etc.) In that way, the chances of any one tape working is high because it was only used once prior to it being needed, and if any one tape fails, there are others created before or after it that can fill in the missing pieces.

What makes tape an attractive backup medium is that tapes are cheap; the cost per megabyte is lowest for tape than for any other medium. So you can have 10, 20 , 50 or hopwever many tapes you want, each of which can contain a full backup, and if any one tape fails, you've got lots of others that might do better (though the chances of that will decrease over time.)
TCav is offline   Reply With Quote
Old Dec 11, 2007, 10:13 AM   #18
Senior Member
 
Join Date: Jul 2005
Posts: 200
Default

A major reason for using tape rotation for back-up is that you have a better chance of retrieving valid data. Data can come corrupt and all you are then doing is backing up corrupt data. In my experience, very few organisations with large installations regularly carried out a restore function to check data validity due to the disruption caused. Even if they run mirror systems in separate secure installations, the hassle of restore is too great due to the interaction with other internal and external computer systems and computerised devices, and the likleyhood of something going wrong is very high.
1eyedeer is offline   Reply With Quote
Old Dec 11, 2007, 10:15 AM   #19
Senior Member
 
BillDrew's Avatar
 
Join Date: Jun 2002
Location: Hay River Township, WI
Posts: 2,512
Default

With any medium (including stone). the only way to achive a good archive is to refresh frequently, i.e., make a new copy on new media. With stone, the data would have to be refreshed every several decades with limstone or sandstone or every few millenia for granite. With tape or optical storage, refreshing every year should be good. So tape can be as good an archival media as any other if it is handled right. Any media will not be good enough if it is not handled right.

Simply producing fresh backups and keeping them will not do the job since something is likely to have been deleted/modified/overwritten. If you want to keep an archive, the existing one needs to be refreshed, not produce a new one.

Refreshing also means copying to new media - how many folks can read a 5.25" floppy let alone an 8" floppy? At the pace things seem to be moving, simply updating your archive to new media (floppy to CD to DVD to BlueRay to ????) when it becomes avialable might be frequent enough.
BillDrew is offline   Reply With Quote
Old Dec 11, 2007, 11:53 AM   #20
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

BillDrew wrote:
Quote:
Refreshing also means copying to new media - how many folks can read a 5.25" floppy let alone an 8" floppy?
Me. I've still got multiple working PCs with 5 1/4" floppy disk drives. lol

But, I do copy anything important to newer media from time to time.

I've got lots of hard disk drives sitting around (and some off site). Each time I upgrade a PC, I tend to copy it's drive contents, too. That way, I have the old drive, and a new drive with the same data.

I seem to be doing that kind of thing more frequently lately. When I upgrade a drive, I'll copy everything from the old one to the new one (usually in a separate partition), as well as have a backup on an external drive. That way, I've got multiple copies of anything I may want later.



JimC is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 7:47 PM.