The InfoSec Blog

How to decide on what DVD backup software to use

Posted by Anton Aylward

You do do backups don't you?  Backups to DVD is easy, but what software to use?

Backup and Restore

  • Do you want the DVD backup 'mountable'?
    If it is then you can see each file and selectively restore using the normal file management tools (cp, rsync etc)
    If you use some sort of 'dump' format (tar, cpio, zip or proprietary) then you will need the corresponding tool to access the backup
  • Why not simply k3b?But if it some down to it, there's a decision tree you can and should work though.

My choice, based upon both K.I.S.S. and bitter experience is to go with the mountable.

  • - How are you 'snapshoting' your files?
    If you are backing up a live system[1] then there is the risk that the backup is out of phase with itself as files get changed during the time it takes to make the backup.

My solution to this is to use the snapshot mechanism of LVM.

English: Linux Logical Volume Management (LVM)...

Logical Volume Management

  • - How are you managing the backup archives?
    Do you need a specific dated version of a file or directory?
    Would a VCS be more appropriate than a backup system?

Sometimes you need both. I maintain changes to config (mainly in /etc/) with a VCS - AND take periodic snapshots.

  • Ultimately its not about making backups, even if that seems to be the
    most of the work, but the ability to restore.

A client found it easier to take whole image backups but once when having to restore a single file there was a finger-slip and he restored the complete machine state of three years previously, loosing all that days work plus the next day when the machine was out of service being restored to the last (previous) backup. The moral here is that your RESTORE strategy, as determined by your normal business functions and NOT by the convenience of the IT department, should determine your backup strategy.

  • - How "automated" do you want this backup to be?
    Sometimes you'll find the automation tail wags the normal operation dog.

My use of K3B means I do disk-to-disk-to-DVD. (Using LVM's snapshots)
It also means I structure my file systems so that they can be imaged onto a DVD. It means I can retrieve single files or mount the DVD and use it in place of the file system. It also means that I can create arbitrary backups, cherry-picking the files and folders to backup.

I realise this is going to be inappropriate for many sites and business functions.

This is why I STRONGLY suggest that instead of simply asking for suggestions you work through what are the key, the critical and the nice-to-have features of your backup AND RESTORE functionality.

Any package you might choose is going to have constraints and assumptions about The Way Things Are. You need to be aware of those and need to consider if they fit in with The Way You Work. A backup system that works well for a data center of ISP might be totally inappropriate and troublesome for a SMB.

[1] Once upon a long time ago systems were shutdown or all jobs
suspended for the backup. This has disrupted projects for me a number
of times.

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Is it the end of the road for LiveCDs?

Posted by Anton Aylward

An Imation USB Flash Drive and CD-R (can be av...
Image via Wikipedia

No. I don't think so!

The price of recordable DVDs is now under $0.22 each That's roughly 60 times cheaper than the current price for equivalent-size pen drives and more than 25 times the cost of the cheapest pen drives now being sold.  And at most trade shows even the more expensive form, the credit card/business card format is being handed out like candy.
Yes, USB sticks are being handed out too, but not so eagerly.

Until pendrives can get Blank-DVD-level cheap -- maybe inevitable, but not at least for five years or so -- it will be cheaper to pass around bootable DVD media than bootable pen drives.   Right now the USB-as-demo works fine so long as you hang around for the demo but is useless for a "try it on your own time" leave-behind (unless you like spending that kind of money for leave-behind, which may work for a reseller but not volunteer advocates).

All media is on a price curve. Its not the price of blank CDs/DVDs that counts, its that they can be printed. Yes, I can download and burn onto a blank, but if I'm in business I'll get 10,000 printed and silk screened, and because of the way printing works the set-up is amortized over volume and that can never be approached by pen drives.

This was the same economics that meant a cassette tape album was often more expensive than a vinyl one and the CD was even cheaper!

You know all this ... But its the price CURVES that are interesting. Blank CDs/DVDs are comparable to blank pen drives, so the price curves CAN be compared. CDs are ahead (in time) and the question is will their price bottom out as the cost of memory falls?

The falling cost of system memory makes the slow speed of LiveCD irrelevant. The $2,000 high end laptop of three years ago now costs under $700 and has 3G or 4G of memory rather then 1/2G. The compressed file system is loaded into memory and the dual (quad?) core CPU running 50% faster (3GHz rather than 2GHz) is so fast that this actually beats out installing on the hard drive!

No, the LiveCD isn't going away any time soon!

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