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Don't Use RAR

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Re: Don't Use RAR

#181

Post by TheFreim »

deelowe wrote: post #166
TheFreim wrote: post #111

Earlier quoted context omitted.

I'm not familiar with compression very much, what's the difference between what 7z does versus "archive recovery"? Thanks

Some compression formats are actually designed for data archival and compression. Rar is one such format. One of the early use cases was data archival onto long term storage mediums such as tape. As such, it has built in parity which means you can recover partially corrupted archives. It can also do things like split the archive up over many smaller files. Again, because this sort of thing was needed for backing up t…

> It can also do things like split the archive up over many smaller files.

Are there other archival formats on par with RAR without the licensing voodoo I see people mentioning?

Re: Don't Use RAR

#182

Post by causi »

useFAR wrote: post #155
lifthrasiir wrote: post #92

Earlier quoted context omitted.

I believe "us[ing] RAR" here means the creation of new RAR files. In fact your experience strikes me as another reason to actively avoid RAR; there is no guarantee that your RAR archive can be decompressed with third-party softwares other than WinRAR itself.

>>In fact your experience strikes me as another reason to actively avoid RAR; This is only your reason. >>there is no guarantee that your RAR archive can be decompressed with third-party softwares other than WinRAR itself. I'm perfectly fine, that my personal files would not be opened by someone, who is actively avoiding RAR(in my personal use - after rar was lha, that I used for archiving, because no one else knew w…

Right. Because I'm a fan of not starving to death myself, I have no problem paying people for goods and services and hence don't agree with the "closed source is a sin" stance of the author. RAR is both faster and more pleasant to use on a daily basis than 7zip, so that's what I use for all my own files. If I'm going to host data or send it to someone who I know uses 7zip, then I'll use that. Generally though when I have a need to send compressed files I have no idea what the recipient has installed so I'm forced to use regular zip files.

Re: Don't Use RAR

#183

Post by noAnswer »

jillesvangurp wrote: post #157
noAnswer wrote: post #50

RAR is a full-blown backup format* while 7zip is "just" an archive format. So comparisons are somewhat mood. But even I as a RAR fan and license holder have to agree. For the average joe, sending email attachments, zip or 7z is enough. * It can safe all three file timestamps (From nanoseconds precision (with NTFS), down to only 2 seconds precision (if you want to shave of a view bytes)), ACLs, ADS, Hard and Soft Link…

I think for the common use case of distributing giga bytes of data in a reasonably efficient way, 7zip is fine (e.g. simheaven.com uses that for huge scenery downloads). Where things get tricky is splitting the resulting archive in multiple files. This used to be common with rar and I think 7zip also supports this. That is convenient when downloading over a slow/unstable connection (or if you don't know how to resume…

The reason I'm a RAR fan is because TAR failed me multiple times! (The first one was ~21 years ago. I lost most of my home.tar.gz-Backup. Because tar has no index, if something bad comes along, everything after that can't be read.) 17 years ago, I took a deep dive into rar and replaced my tar.gz backup process with it. I had a cronjob that checked the tar.gz-Backups from the past week and there was a 50% change of "Unexpected EOF in archive". There where weeks, when all seven archives had and error! Disk, NFS, USB-Stick didn't mater. Also I wanted encryption. Which means another pipe. I have also seen bit flips on USB-Sticks. Where a copied jpg had reversed colours in the middle. So I wanted redundancy too. RAR has everything included, and I felt it had a low bus factor.

Time moves on. 7zip feature creeps towards rar. Most if not all consumer OSs can open and create .zip out of the box. So, who cares ;-) Even I use Borg for my backups these days, since I don't have to care about a bus factor any more. RAR is still cool and my 17 year old licence is still valid.

Re: Don't Use RAR

#185

Post by bo1024 »

kazinator wrote: post #140
mimsee wrote: post #125

Earlier quoted context omitted.

Could I then download a zip of torvalds/linux from github and use it without abiding by the license as it’s never thrown in my face?

Yes. The GPL is not a license which dictates how you can use software, such as that you must not read it, or use ideas from it. EULA restrictions like "no reverse engineering" are not rooted in copyright law, and borrowing ideas is in the realm of patents. EULA's try to leverage copyright law in order to impose non-copyright restrictions, using the concept that if you violate any of the arbitrary non-copyright restri…

I always found this aspect of 'copyright' very confusing. I still don't understand the legal basis here.

Re: Don't Use RAR

#186

Post by computator »

ronjouch wrote: post #153
xtracto wrote: post #146

Earlier quoted context omitted.

RAR is the only archive/compression format that can include a PAR2 like recovery record. You can even configure what % of the size to dedicate for that. That has been a great killer feature for me over the years.

Confirming this, and confirming that the recovery record (that I had set to a hefty 10%, I think, because the data was important to me) did let me recover archives that suffered physical media damage, which would have been irrecoverable had I used something else. I wish 7zip had this feature. This was one of the most satisfying progress bars: from "your data is dead" to a few minutes later "Successfully recovered ful…

> let me recover archives that suffered physical media damage

> Usability nit aside, I'd love to hear about alternatives.

Make two or more copies on different media. Sure, RAR or another archiver can save you from partial media damage but nothing saves you from total media damage other than having completely separate backups.

Re: Don't Use RAR

#187

Post by ComputerGuru »

lifthrasiir wrote: post #78
ramraj07 wrote: post #69

Earlier quoted context omitted.

But slower.

It depends on which time you measure. 7zip's LZMA2 is, like most LZ algorithms, asymmetric that it is quite fast to decompress no matter how much you spend on the compression. By comparison RAR uses PPM in the highest setting, which is more or less symmetric so the compression and decompression takes about the same amount of time. When the target ratio is roughly same and high enough, LZMA2 is indeed slower than (RAR…

There is no world in which LZMA2 decompression can be considered “quite fast.” It’s decompression speed bears no resemblance to that of other LZ algorithms like LZ4 (which is definitely fast).

https://www.opencpu.org/posts/brotli-benchmarks/

Distributions have stopped using xz/lzma in favor of slightly inferior (size-wise) alternatives due to the time and memory decompression requirements of lzma.

Re: Don't Use RAR

#189

Post by nine_k »

computator wrote: post #186
ronjouch wrote: post #153

Earlier quoted context omitted.

Confirming this, and confirming that the recovery record (that I had set to a hefty 10%, I think, because the data was important to me) did let me recover archives that suffered physical media damage, which would have been irrecoverable had I used something else. I wish 7zip had this feature. This was one of the most satisfying progress bars: from "your data is dead" to a few minutes later "Successfully recovered ful…

> let me recover archives that suffered physical media damage > Usability nit aside, I'd love to hear about alternatives. Make two or more copies on different media. Sure, RAR or another archiver can save you from partial media damage but nothing saves you from total media damage other than having completely separate backups.

Two copies is 200%, the redundancy records are normally below 110%.

It's like RAID1 vs RAID5, only without the speed bonus of RAID1.

Re: Don't Use RAR

#190

Post by ronjouch »

nine_k wrote: post #189
computator wrote: post #186

Earlier quoted context omitted.

> let me recover archives that suffered physical media damage > Usability nit aside, I'd love to hear about alternatives. Make two or more copies on different media. Sure, RAR or another archiver can save you from partial media damage but nothing saves you from total media damage other than having completely separate backups.

Two copies is 200%, the redundancy records are normally below 110%. It's like RAID1 vs RAID5, only without the speed bonus of RAID1.

Yeah. They have a point, though, more copies is good too.

To me it's a case of “why not both?”, and I remain interested in software free RAR alternatives with a RecoveryRecord-ish feature.

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