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Old 2nd February 2018
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Default Backup to DVD-RAM?

I recently came across a stack of dvd-ram disks I'd forgotten I had - they were used with a consumer DVD rewriter I no longer use. There's about a dozen disks, many in their original packaging, unused.

So, I was thinking of using them as backup media for my OpenBSD laptop. Up till now I've been using rsync, backing up to an external drive on the network. It works well enough, but is not ideal.

DVD-RAM disks use, from what I understand, packet writing, so the disks can be treated in a more conventional way.

I have a couple of questions:

1. Are dvd-ram disks a good medium for backup? Bearing in mind the total size of the data I wish to backup (i.e. the /home partition) is only about 5Gigs and is unlikely to rise much above two or three times that amount, at least for now.

2. Any recommendations of the best backup software to use? I'm only backing up the /home partition, so a fairly simple approach is probably best... Would dump/restore be a good choice?

Thanks for reading. Comments welcome.
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Last edited by ip6ix; 2nd February 2018 at 01:04 AM. Reason: clarification
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Old 2nd February 2018
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Quote:
Originally Posted by ip6ix View Post
1. Are dvd-ram disks a good medium for backup? Bearing in mind the total size of the data I wish to backup (i.e. the /home partition) is only about 5Gigs and is unlikely to rise much above two or three times that amount, at least for now.
Sure, if you can live with the 4.7 GB max capacity of the disks.

Quote:
Originally Posted by ip6ix View Post
2. Any recommendations of the best backup software to use? I'm only backing up the /home partition, so a fairly simple approach is probably best... Would dump/restore be a good choice?
What are you trying to back up? Just some files? dump(8) is pretty good then. Or you could go real basic and do something like:
Code:
$ cd
$ cd ..
$ doas tar -cz -f ip6ix-`date +%Y%m%d` ip6ix/
Which would simply make a tarball of your $HOME (assuming your username is ip6ix). And then you can drop the tarball onto your DVD-RAM.
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Old 2nd February 2018
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Should you want to manage multi-disc volumes, you may find sysutils/shunt helpful. From the package description:
Quote:
The shunt utilities: shunt, exactly, and flyisofs, were originally
written for burning multi-set CDROM backups using mkiosfs and cdrecord.

The key utility -- shunt -- manages recursive access to piped I/O, so that
programs may be re-run without causing a pipe to close.
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Old 2nd February 2018
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I also use the tar command but add the compression flag for gzip. Given that your /home directory is about 5GB, compression might be enough to get it all on one DVD.

My data fell in to two categories, ripped mp3's and other. My "other" data is frequently updated and includes emails You can feed the tar command a list of files/folders and be selective about what you back up. I have not ripped mp3 in several years.

As far as the durability of DVD disks, I read somewhere, that standard disks could be relied on for about 10 years. I believe that there are some newer DVD touting more durable data storage but not sure sure that the improved durability is anything more than hype.

Last edited by shep; 2nd February 2018 at 03:53 PM.
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Old 3rd February 2018
e1-531g e1-531g is offline
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Quote:
Originally Posted by shep View Post
I also use the tar command but add the compression flag for gzip. Given that your /home directory is about 5GB, compression might be enough to get it all on one DVD.
Compression can be dangerous. In some compression formats corruption of one byte can lead to unability of decompression of whole archive. Probably some modification to decompression algorithms would allow to recover at least some data, but they are not currently able to do that. I can confirm that on xz archives.
You can counter that using tools like "par2cmdline", but they add redundancy making files larger. Some file formats are compressable to pretty good degree for example text files. For text files compression and later adding redundancy can make resulting archive smaller overall.

Quote:
Originally Posted by shep View Post
As far as the durability of DVD disks, I read somewhere, that standard disks could be relied on for about 10 years. I believe that there are some newer DVD touting more durable data storage but not sure sure that the improved durability is anything more than hype.
I don't think that there are large investments in DVD storage nowadays. I wouldn't count on today discs and DVD recorders being more reliable that its 10 years old counterparts.
If you have DVD recorder in your non-budget desktop's system unit from 2008 I would prefer that recorder than today recorders.

Record DVD at medium speed for improved durability. There were tests that showed low speed and maximum speed recording are making more writing errors than medium speed recording.
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Last edited by e1-531g; 3rd February 2018 at 09:30 AM.
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Old 4th February 2018
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Many thanks to everyone who responded.

Shunt looks quite interesting, I'll take a look at that more closely later, thanks jggimi.

Since the size of the backup is relatively small (and consists mainly of text), the compression ratio is good. With compression this will easily fit on one disk. I might add par2 verification using par2cmdline also, this seems like a good idea for important data (though I tend to make more than one backup at a time, so may be overkill).

I wanted to create a UDF filesystem on the dvd-ram disk, as this would be a very convenient way of accessing the dvd for backup purposes, but it seems this is not (yet?) available in OpenBSD. I can mount an already formatted udf volume using mount_udf(8), but it's read-only.
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Old 4th February 2018
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Quote:
Originally Posted by ip6ix View Post
...but it seems this is not (yet?) available in OpenBSD. I can mount an already formatted udf volume using mount_udf(8), but it's read-only.
See sysutils/udfclient.
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Old 4th February 2018
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Quote:
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See sysutils/udfclient.
Perfect. Thanks jggimi
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