Storing data on DVD media with recovery

[kyrcy]

I usually store data on DVD media in a rar archive with recovery record and when there is free space I also add error correction data using dvdisaster. Is anyone using a similar approach or can recommend a better one?

[dannyboy48888]

Use to do that or dvdisaster, now i just make my folder of files and run multipar on it then burn with imgburn if there's a error I read the disc with isobuster and then check/repair the contents

[SameSelf]

+1 for appropriate cold storage
+1 for ECC
-1 for putting the ECC file on the same disc/only generating if there is room on the disc (I am not sure what you really meant here)
I would add that BD-R are an affordable option at around 4-5 cents/GB last I checked for DL (doesn't include the price of a burner). And even TL are becoming reasonably priced due to I assume the arrival of UHD BD. Those are my go to medium. I generate TB's of data so DVD is not an option. In fact some of the master video files I generate exceed 50 GB.
Also, I don't compress my archives because the bulk of it is video masters and compression is useless.

[kyrcy]

I do not work with large files to need BD-R. The largest files I usually put on dvd media are around 10GB and I split these on multiple volumes. I always use recovery record with rar archives and if after splitting on multiple volumes there is still free space on the discs I add error correction data with dvdisaster. Otherwise I only use recovery record with rar archives. I have never used multipar. Is there an advantage to use that instead?

[dannyboy48888]

With multipar I noticed recovery speed to be a lot faster. Also if the media is error free I can copy the files not the ecc saving time. Dvdisaster image rebuild took 25mins while multipar was done in 5-10 on test disks I made

[KarMa]

Bluray can be about half the cost (depending the brand) per GB than DVD. Bluray also uses HTL dyes (unless stated to be LTH) which arguably have better longevity over DVDs (which are always LTH). But then again I still have 13 year old DVD-Rs that play and read fine. As far as using ECC on data discs, I use PAR2 corrective data that can be created with Multipar. I simply put the files as is on the disc, not in a RAR or 7zip unless I need to split the files across two discs, and accompany it with PAR2 data to fill up the 100s of extra MBs. Multipar has a nice little widget to take into account how big your files are and which data disc you are using (DVD/Bluray) to create PAR2 files just large enough to fill the disk to nearly 100%.

PAR2 works on blocks and so the smaller the block, the more random errors across the disc it will be able to correct for. If two errors happen in a single block, it just needs one corrective block to fix it. If two errors happen in two separate blocks it needs two corrective blocks. So if you set your PAR2 data to use larger and few blocks it will take much less time to create the PAR2 data but the number of random/spread out errors it will be able to correct for will be greatly diminished.

-1 for putting the ECC file on the same disc/only generating if there is room on the disc (I am not sure what you really meant here)

Lets say you have 24.5GB of data to put on a 25GB disc. To completely fill up the disc you fill up the rest of the space with ECC, otherwise the space is wasted anyway. I would also have to ask why putting ECC on the same disc is so bad? With PAR2 any errors in the PAR2 data is found and just simply not used by excluding that corrective block. If you are going to put ECC data on another disc, might as well just do a duplicate backup.

[kyrcy]

Do you mean that I could use recovery record with rar archives and also multipar instead of dvdisaster? Last time I checked (a few months ago) blu-ray was about the same cost as DVD. And HTL were much more difficult to find and expensive to buy than LTH which is the majority of media currently available.

[KarMa]

Do you mean that I could use recovery record with rar archives and also multipar instead of dvdisaster?

Not sure if this was directed at me but I'll give my input anyway. I'd just use PAR2 data (multipar) as the recovery method and not use RAR recovery, but you can still use basic RAR if you want without RAR recovery. Or just pick one or the other, don't want to create recovery data for recovery data.

Last time I checked (a few months ago) blu-ray was about the same cost as DVD. And HTL were much more difficult to find and expensive to buy than LTH which is the majority of media currently available.

All BD-R discs are HTL unless LTH is stated. While there's a lot of variation in the BD-R and DVD-R disc prices, generally 25GB BD-R is about half the price per GB. For comparison, Verbatim 25GB cost around $0.026 per GB compared to Verbatim DVD-R at 0.053 per GB.

[kyrcy]

My current strategy as I tried to explain above is to use rar recovery record and sometimes add dvdisaster error correction when there is still free space on disc. I do prefer to store recovery record inside an archive and I don't like the "mess" multipar makes by creating several files that need to be stored on disc. Dvdisaster error correction data is "invisible" on disc. I understand that if I need to create multiple volumes I have to stick to rar anyway. So if I am sticking to rar, why should I not use it's own recovery and use multipar instead? Speed is not enough reason for me to make the change. I can only buy BD-R discs that are LTH locally and prices here (having checked again) are still not much cheaper compared to DVD media. And it seems that there are only few choices when looking for a blu-ray writer and these seem to be decreasing every day.

[KarMa]

Seems like you can't pick block sizes in WinRAR Recovery Records but can only pick redundancy as a percentage of the files to be put in the RAR. I have no idea how big the RAR blocks are and there does not seem to be much info on the subject. Also PAR2 can be created to just about any size. So even if you only have a small amount of left over space, which most times you will unless using custom sized RAR files. So you can fill even tiny voids with PAR2.

As far as buying a Blu-ray drive. They can be had for pretty cheap only for $40-$70, for normal consumer grade drives.

[kyrcy]

With rar I only choose percentage that makes life easier. With PAR2 should I stick with the default values or change something? Fit to free space seems very useful, but besides that what else?

[KarMa]

With rar I only choose percentage that makes life easier. With PAR2 should I stick with the default values or change something? Fit to free space seems very useful, but besides that what else?

Well you usually want to divide your data into the most number of blocks to help with random errors that one might expect on a data disc. But having more blocks equals longer build times. To have more/smaller blocks, move the "Block Count" slider to the right, then after picking out the block size just click fit "fit to free space".

PAR2 vs WinRAR Recovery Records seems to just be more of a question of control over the settings. Info on Winrar RR seems hard to come by but both Winrar and PAR2 use Reed–Solomon error correction, so they both should give the same level of ECC if both are set to the same block sizes and the amount of redundant data. But with Winrar being proprietary it's hard to say, compared to Par2 which is more open.

[kyrcy]

When I am going to fill a disc completely, I use 10% recovery record for each archive. If I am going to split a file into rar volumes and I know these will not fill completely all discs, I use 100% recovery record and if there will still be some space left, I add dvdisaster error correction. I think this provides extra recovery without wasting the unused space even if it is recovery data for recovery data.

[lordsmurf]

BD-R is not archival. Too fragile, essentially inverted CD-R.
Relying on software like dvdisaster is probably not wise, and will probably not exist in the future.

[kyrcy]

I never tried BD-R media, but I have been burning DVD-R and DVD+R media for backup the last 10 years with no failures. Verbatim AZO mainly, but even cheap ones seem to read fine after so many years.

[KarMa]

BD-R is not archival. Too fragile, essentially inverted CD-R.

Not really sure what would meet your definition of archival. And if by inverted you are talking about using HTL instead of LTH found in CD and DVD, then you might consider the fact that LTH BD-Rs perform worse than HTL BD-Rs in accelerated aging tests. The tests being storage in high heat and high humidity conditions and a separate test being put in front of a Xeon-Arc lamp.

https://francearchives.fr/file/5f281a39048987dcef88202816a5c8ade880552e/static_6187.pdf

[lordsmurf]

Not really sure what would meet your definition of archival. And if by inverted you are talking about using HTL instead of LTH found in CD and DVD, then you might consider the fact that LTH BD-Rs perform worse than HTL BD-Rs in accelerated aging tests. The tests being storage in high heat and high humidity conditions and a separate test being put in front of a Xeon-Arc lamp.
https://francearchives.fr/file/5f281a39048987dcef88202816a5c8ade880552e/static_6187.pdf

I'm talking about the physical structure of the disc, not HTL/LTH writing method. Physically it is a huge plastic platter on top, with this razor-thin easy-to-damage surface on bottom. They must coat BD-R in an anti-scratch gloss, but long-term it won't last.

https://en.wikipedia.org/wiki/Durabis

Heat/moisture tests in a lab completely bypass this larger issue.