Using flash cards for backups.

[Demon-Xanth]

Now that you can get a 16GB flash card in the $30 range, I was thinking rather than back stuff up to DVD-Rs and such, would backing it up to a flash card be a better idea? There'd be no chance of it getting scratched and made unreadable, and data can be updated when needed rather than rewriting everything.

Discuss.

 

[Modelworks]

Depends on how long you want to store the data. Flash has a shorter life span than recordable media. Estimates are 10 years before bits start to change. That is just in storage with no writes being done. If the drive is stored in a thick lead box it might also extend the life of the data stored.


I tell people to just make a couple dvd of the same data and store that in a cool dark place. With multiple copies of the same data you can always recover the whole set if one part is bad on each disc.

 

[taltamir]

CLAIMED data life is about 10 years (from writing it, not from purchasing of the device... aka if you rewrite the data 5 years through it will last 10 years from that point) on a flash device before degrading.
From my experience data on CDs degrades FASTER than that...

However there is a special format for optical media that uses a large portion of the space for recovery data, so even a few errors here and there will not make the data unrecoveable.

personally I use raid6 + ZFS... ZFS has everything hashed. So if there is an error on a drive it KNOWS which drive error (compared to regular raid, in which the data is lost because it doesn't know which drive has the correct data). The data is also repaired on the drives in real time if there is a copy of it elsewhere on the array.
Just run a "scrub" operation every now and then and you will never lose data.

 

[techmanc]

"However there is a special format for optical media that uses a large portion of the space for recovery data, so even a few errors here and there will not make the data unrecoveable."

So what are they putting some kind of parity data on media as I use quick par to add that info on some of my data CD/DVDs?

 

[Elixer]

Originally posted by: techmanc
"However there is a special format for optical media that uses a large portion of the space for recovery data, so even a few errors here and there will not make the data unrecoveable."

So what are they putting some kind of parity data on media as I use quick par to add that info on some of my data CD/DVDs?

You can think of it as parity data. However, after a certain threshold, no amount of parity will recover the data.

It is still better to have your own par2 files and be able to recover your files that way. Of course, if you can't ever read the CD/DVD, then your screwed.

I also think that CD/DVD media (even the expensive stuff) don't last longer than 6 years in a normal environment.

 

[taltamir]

So what are they putting some kind of parity data on media as I use quick par to add that info on some of my data CD/DVDs?

That is exactly what they are doing, sure you can use quickpar, but this is neater implementation, its an open source filesystem.

It is still better to have your own par2 files and be able to recover your files that way. Of course, if you can't ever read the CD/DVD, then your screwed.

If they use equivalent parity format, then the amount of data loss needed to be unrecoverable is the same as if you use par files.

I also think that CD/DVD media (even the expensive stuff) don't last longer than 6 years in a normal environment.

In a sealed case, 72 degrees constant, not exposed to light or anything else for that matter... 1/3 of my 1000 disks was unreadable within 2-4 years.

Which is why today I use ZFS + RAIDz2 (raid6 with ability to recover individual sectors by having hashes of all files in addition to regular parity)... Now my data is safe. CDs and DVDs are shit for long term storage.

 

[techmanc]

"In a sealed case, 72 degrees constant, not exposed to light or anything else for that matter... 1/3 of my 1000 disks was unreadable within 2-4 years."

I would think theres a huge degree in the quality for CD/DVDs today vs some of first years the media was made. Not sure how that plays out in years before media degrades but there must be some kind of relationship.

Also anyone who relies on only original media not matter which type with no backups and even backup of backups is in for trouble IMHO.

 

[taltamir]

it was all burned disks actually. and were not very valueable, i can redownload anything that was on there...

But I am saying that if you DO decide to say, backup your family photoes, don't expect the backup CD to work.

 

[taltamir]

mmm, i can't seem to find that filesystem, and i can't seem to remember exactly how it works

 

[taltamir]

found it... http://dvdisaster.net/en/
it uses a reed-solomon ECC algorithm, which is what is used in parchive (par and par2)

 

[Elixer]

Originally posted by: taltamir

I also think that CD/DVD media (even the expensive stuff) don't last longer than 6 years in a normal environment.

In a sealed case, 72 degrees constant, not exposed to light or anything else for that matter... 1/3 of my 1000 disks was unreadable within 2-4 years.

Ack! It sucks that we don't have decent, cheap, reliable archival storage. Looks like tape is about the only thing that can last a long time.

Which is why today I use ZFS + RAIDz2 (raid6 with ability to recover individual sectors by having hashes of all files in addition to regular parity)... Now my data is safe. CDs and DVDs are shit for long term storage.

ZFS? You using solaris?

 

[techmanc]

I just downloaded and installed dvdisaster software will post an update after I have time to try it.

 

[rarebear]

OP,
I think any back up is much better than no back up..

I to have lost a lot of CD/DVD media..

A first I thought it was become I just got a 24X CD R and was using it at 24X and 8X media but now burn movies and they because unusable in a few months some time..

The more types of media you use for backups the better...

 

[taltamir]

Originally posted by: Elixer

Originally posted by: taltamir

I also think that CD/DVD media (even the expensive stuff) don't last longer than 6 years in a normal environment.

In a sealed case, 72 degrees constant, not exposed to light or anything else for that matter... 1/3 of my 1000 disks was unreadable within 2-4 years.

Ack! It sucks that we don't have decent, cheap, reliable archival storage. Looks like tape is about the only thing that can last a long time.

Which is why today I use ZFS + RAIDz2 (raid6 with ability to recover individual sectors by having hashes of all files in addition to regular parity)... Now my data is safe. CDs and DVDs are shit for long term storage.

ZFS? You using solaris?

for my file server. i bought 5 x 750GB HDDs (wd greenpower, because they were cheapest, about 120$ each). I sold my athlon x2 and bought an energy efficient x2 instead, and used an old 160GB IDE drive for the OS.
And I am happily running a fileserver with opensolaris.

ofcourse, i really should use dvd backups... if someone burgles my home they are bound to take my filerserver

 

[Modelworks]

What are you guys doing to your backups to make them fail so often ?
I have dvd media that is back from when you could only get 2x burn speeds that still reads fine.

 

[taltamir]

oh, when choosing burn speeds... typically the least errors occur when using a speed ONE below the max of your drive... so if your drive can burn a DVD in : 1x, 2x, 4,x 6x, 8x, and 12x. choose 8x...
Or you can test your own drive because that does vary, but one below max is a typically very safe speed to burn in to minimize correctable errors.

 

[techmanc]

What I do for more reliable and faster burns is now the new burners are cheap $25-$30 update my 2 burners at least once a year and use decent media.

 

[Modelworks]

Originally posted by: techmanc
What I do for more reliable and faster burns is now the new burners are cheap $25-$30 update my 2 burners at least once a year and use decent media.

I think the media is the key.
The old disc I have were burned 5 years ago and still read fine are verbatim media. The disc I use now are sony accucore. It is more expensive media but I rather pay that and have something that will last.

I also do not put labels or print on the media, just mark on it with a sharpie. Seems labels and inkjet printing on dvd cuts the life span .

 

[tm37]

The key to backup is that you have it in two places.

Your hard drive may fail and your Back up may fail.

The priniclple of back up is that they will not fail at the same time

my preferred meathod is an external hard drive that does the back up automatically. (one a week or so)

 

[taltamir]

The priniclple of back up is that they will not fail at the same time

Yes, but what if the backup fails silently, for all you know it failed a year ago and you never noticed.