SOLVED How reliable is zipping in Windows 7 Explorer?

[seveny]

There have been times in the past when a zip file I created was corrupt (or became corrupt somehow). I encountered this either using WinZip or command-line zip, possibly in old Unix environments. To me, there is a risk in relying solely on zip archives and deleting the original unzipped files. The risk isn't only in losing one file that is corrupt -- any corruption anywhere in the entire archive could render all the files therein inaccessible. Hence, the risk increases with the size of the archive.

How reliable is the zip that is native to Windows 7? In addition to that general question, what about specifically for files in the Gigabyte range (fraction of a GB or several GBs)? If it is very reliable, then I will use the Windows 7's "compressed (zipped) folder" to create archives for writing to DVD.

I am using Windows 7 Professional 64-bit. I want to avoid discussion about Windows 7 backup as it is not suitable for my specific purposes.

 

[TrainableMan]

Corruption is caused by hard drive problems and is not the fault of the zip program. Drives loose their ability to hold a charge in certain places and if that location happens to be a part of an active file then the file is "corrupted". The bigger a file is the more sectors it takes and therefore the greater possibility.

 

[clifford_cooley]

Corruption is caused by hard drive problems and is not the fault of the zip program.

Thats what I was thinking but was reluctant to comment.

 

[seveny]

Thanks Trainable.

 

[Digerati]

To me, there is a risk in relying solely on zip archives and deleting the original unzipped files. The risk isn't only in losing one file that is corrupt -- any corruption anywhere in the entire archive could render all the files therein inaccessible.

The risk is the same regardless the compression used. Frankly, with the cost of disk space, I see no reason to zip or compress files - except perhaps to send over the Internet.

Corruption is caused by hard drive problems and is not the fault of the zip program.

I mostly agree with this, but not entirely. Corruption can occur in memory during the compression/decompression process too - caused by the zip program, an OS hiccup, or some other hardware issue - memory fault, power fluctuation, etc. This is exactly why most better compression programs have a validation or checksum process.

You say you don't want to deal with Windows 7 Backup. Okay but note (1) Windows 7 backup is a very capable backup utility and (2) zipping files for archival purposes is not.

 

[seveny]

I wrote:
> To me, there is a risk in relying solely on zip archives and
> deleting the original unzipped files. The risk isn't only in losing
> one file that is corrupt -- any corruption anywhere in the entire
> archive could render all the files therein inaccessible.

Digerati wrote:
> The risk is the same regardless the compression used. Frankly, with
> the cost of disk space, I see no reason to zip or compress files -
> except perhaps to send over the Internet.

I want to take snapshots to separate discs. I'm not all comfortable collecting successive snapshots onto a single HD. I don't like the idea of keeping half a dozen HDs just to rotate among them. Also, I can drop a disc and still expect it to work.

Quote:
> Corruption is caused by hard drive problems and is not the fault of
> the zip program.

Agreed. However, I am still concerned about the risk associated with compression.

Digerati wrote:
> I mostly agree with this, but not entirely. Corruption can occur in
> memory during the compression/decompression process too - caused by
> the zip program, an OS hiccup, or some other hardware issue - memory
> fault, power fluctuation, etc. This is exactly why most better
> compression programs have a validation or checksum process.
>
> You say you don't want to deal with Windows 7 Backup. Okay but note
> (1) Windows 7 backup is a very capable backup utility and (2)
> zipping files for archival purposes is not.

Yes, someone suggested QuickPar. It's an interesting solution.

About the greater capability of Windows 7 backup compared to zipping, I don't have to explicitly zip if I simply use the built-in compressed folders. I like the control that this affords in terms of selecting and organizing the stuff to archive. As for the greater capability of Windows 7 backup, I don't look forward to learning new GUI-restricted apps. I don't know what QuickPar is like yet....

Thanks for your comments, Digerati.

 

[Digerati]

About the greater capability of Windows 7 backup compared to zipping, I don't have to explicitly zip if I simply use the built-in compressed folders. I like the control that this affords in terms of selecting and organizing the stuff to archive. As for the greater capability of Windows 7 backup, I don't look forward to learning new GUI-restricted apps. I don't know what QuickPar is like yet....

It is important to note that zipping (compressing) files is NOT and never was meant to be used as a backup method. Compressing a file, or a bunch of files/folders into one file was always meant as a method of saving space - first for saving space on storage devices, then more recently to save bandwidth when transferring files over networks.

I do not recommend compressing files - even with Windows own compression utilities - for archiving purposes. Disk space is so affordable these days. Also note that many files, including most song and video files, don't compress by any significant amount.

 

[seveny]

Thanks again, Digerati. As I mentioned, I'm looking for a solution that doesn't involve backing up to HD.

 

[Digerati]

You can always burn DVDs, or better yet, BluRays - but nevertheless, with today's HUGE hard drives costing pennies per gigabyte, and with HDs being very suitable for long term storage, they are something you should consider.

 

[seveny]

How would you manage the issues that I described?

 

[clifford_cooley]

How would you manage the issues that I described?

If you don't want to backup to another HDD, then backup using Bluray disk. For less than the cost of a 64GB thumb drive you can backup 1TB to Bluray, that is if you already have a Bluray Writer.

The greatest enemy of CD/DVD/BD is the way you handle the disk. They do scratch easily, even under the best of intentions. I personally recommend not using sleeves for storing optical media.

 

[seveny]

Actually, I don't have a Blueray drive. Years ago (seems like yesterday) I bought a DVD writer because my laptop at the time didn't have one. Boy, that sure doesn't serve much use anymore. So if possible I'd like to avoid buying another drive. I can avoid it so long as my backups fit on to DVD. It sure does right now (in fact, it might fit onto CD). I apprecite the suggestion, though. I may resort to it in the future.

 

[clifford_cooley]

The only other option would be to pay a monthly premium for on-line storage. But then that would be throwing your money away even quicker than purchasing a Bluray drive.

 

[Digerati]

How would you manage the issues that I described?

I already said several times I would buy a bigger, or more hard drives for massive amounts of long-term storage and forget zipping/compressing. The cost per Gb is cheaper than burning optical disks and hard drive storage is more robust (pretty hard to scratch the disk, for example).

 

[TrainableMan]

Your DVD burner is still a viable solution if you are willing to limit the files you back up. It is just that Blueray disks hold about 6 times more information than a standard DVD and 3 times more than a Dual-layer DVD.

For instance if you were to back up all of your "pictures" library, for most users they would all easily fit on a regular or DL DVD without any zipping or file compression of any kind.

My entire "Documents" library would fit on a regular DVD and my "music" on a single DL DVD.

But if I had a Blueray burner I could burn all three of those libraries to a single Blueray disk.

Where I would run in to real problems is my downloads folder is 150GB and my videos folders are over 500GB. My downloads include many files I downloaded that are zipped but I would never consider zipping my entire downloads folder as a back-up solution and even Blueray wouldn't be practical IMO.

So I use an external HD because it is practical for my needs, and I don't compress anything, I use a straight one-to-one copy/compare program, Microsoft's SyncToy.

It is important to pick the right back-up method/media based on the volume and frequency of data you have to back up. I just think everyone here is suggesting that zipping files as a back-up solution is probably not your best option. Zipping is fast and reliable as a compression and consolidation method for sending/receiving files via the internet but it isn't really intended as a long-term back-up method.

 

[Digerati]

The problem with "burning" optical disks (whether CD, DVD or BR) is compatibility. I am not talking about protocols and standards changing but rather something more basic - head alignment.

Commercial (burned at the factory) disks are pressed (not really burned) by very sophisticated, very expensive, extremely precise machines and the "tracks" are laid out on the disk with extremely precise and exacting alignment.

That precise track alignment ensures the disk can be played on virtually any player without problems.

Mass produced DVD/BR burners that cost a few dollars each to make, and that have movable R/W heads are not near as precise as disk stamping (pressing) machines so the tolerances of the track alignment on home "burned" disks is not near as precise as factory pressed (pre-recorded) disks. That is not normally a problem when playing (reading) a disk in the same drive that burned (wrote) the disk because any mis-alignment is "off" by the same amount in the same direction (unless the drive was dropped).

The problem comes a few years down the road and you have a different burner in your new computer and suddenly your backup disks are not readable because the tolerance variance of the old writer added to the tolerance variance of the new reader add up to an out-of-tolerance situation. This is especially a problem with budget drives - and who buys the most expensive optical drives they can find?

That is not a problem with hard drives (if not dropped) because the disk platters are read with the same R/W head as they were written to. Also, the data on HDs can easily be "refreshed" (written to the disk again) to ensure data integrity. You cannot refresh the data on a burned disk.

 

[TrainableMan]

The problem with "burning" optical disks (whether CD, DVD or BR) is compatibility. I am not talking about protocols and standards changing but rather something more basic - head alignment.
...
The problem comes a few years down the road and you have a different burner in your new computer and suddenly your backup disks are not readable because the tolerance variance of the old writer added to the tolerance variance of the new reader add up to an out-of-tolerance situation.

Interesting. Sounds possible but personally I've never experienced this problem. I have used the same CDs and DVDs in numerous different computers as well as in replacement DVD drives when the old ones die. I think if I bought one and my old DVDs don't read then I would take it back and buy a different brand.

But still, for sheer volume of data, I prefer a HD for back-up

 

[Digerati]

Interesting. Sounds possible but personally I've never experienced this problem. I have used the same CDs and DVDs in numerous different computers as well as in replacement DVD drives when the old ones die. I think if I bought one and my old DVDs don't read then I would take it back and buy a different brand.

It does not happen a lot - especially with newer burners. I used to see it more often when cheap, higher density DVD burners started appearing. If you find a drive that reads factory disks fine, but fails on disks burned with a different PC/Home type burner, suspect alignment tolerance problems.

But still, for sheer volume of data, I prefer a HD for back-up

Agreed. Especially considering the price of monster drives these days.

 

[seveny]

The only other option would be to pay a monthly premium for on-line storage. But then that would be throwing your money away even quicker than purchasing a Bluray drive.

I agree entirely. I will endeavour to postpone the day on which it becomes necessary to by a Bluray drive by being as efficient as possible with the data that I keep.

 

[seveny]

I already said several times I would buy a bigger, or more hard drives for massive amounts of long-term storage and forget zipping/compressing. The cost per Gb is cheaper than burning optical disks and hard drive storage is more robust (pretty hard to scratch the disk, for example).

Yes, I did noticed that common theme. Cost per GB isn't really the issue in my case, since my data isn't as voluminous as is typical today. I also agree that the degradation of data on the disc media is likely faster than on an HD media. As I said, however, the HD is electronically and mechanically more complicated (and hence less robust) than just the physical media alone. In the overall picture, I'm not sure which one is more reliable. Especially since there is a bit of redundancy from separating snapshots into separate discs (though they are different snapshots, and they aren't geographically separated).

From your response, I guess that your answer to my question is that you simply assess these factors differently for your needs, and the HD comes out on top.