Compression level be gone

I do my imaging without any compression. I think allows for a greater possibility of a successful restore. Sure the images my use a little more room but the backups are done in a simpler manner. All most like going native.

 

I'm not sure I would agree with you. I have done backup and recoveries with all levels of compression, and I have never noticed much of a difference. I certainly do not think my backups with max compression are more likely to fail...

 

The differences will show up on a system that is marginal. The marginal system is good for everyday use but restoring an image that was compressed is to much for it to handle.

 

Sorry, what do you mean by a marginal system?

 

My definition of a marginal system is any system that when STRESSED will have a tendency to breakdown.

 

Furthermore I have had marginal systems that could not make it through a back and/or restore if compression was used.

 

It's not just space, but time that can vary with the level of compression. Assuming the files being backed up are already compressed, then using some comrpession will be faster and using lots of compression will be slower than using no compression.

I have a drive that's 95% jpegs and aac files, which are compressed in their normal state. Doing an image backup of this drive, the tib file ends up about the same size with/without normal compression, but runs much faster without comrpession.

 

Depends on where the marginal component is. If your disk sub-system is marginal transferring an extra 35% of data because the archive is uncompressed is more likely to have the opposite effect.

I would guess that if you have some marginal RAM locations that might come into play when compression is used would support your theory.

Overall, apart from reading/writing the disk, the PC processing components do have more work to do when compression is used. However, the real issue is that the machine is not operating properly and not-compressing is just a work-around.

 

Bingo. You got it. Marginal mother board’s can’t stand compression. The real issue is to have a backup image that can be restored.

 

Well, that and to have a motherboard and ram that work properly ;-)

 

Yes indeed, like I said above, no compression is just a work-around for an imperfect system.

 

No compression also means it can be viewed without mounting and files copied ect. in Windows Explorer--a clear benefit in my view.

 

You can do it from a compressed archive as well.

 

Yep, just tried it on a UDF DVD imaged with the default level of compression and it was visible as you said.

I'm just wondering if a DVD image is visible using 'maximum' compression? Will have to try it someday.

 

Go ahead, compress your backups but remember there will be a point in time when you wish you had listened to me.

 

I agree that in one sense it seems reasonable to take as few risks as possible - in this case not compressing may be seen as being more cautious.
BUT trusting a program to image a complete system and then objecting to one aspect does seem perverse.
Personally I have been making and restoring multiple images per day since version 6 and have had no significant problems. Making compressed images certainly stresses a system - take a look at how the temperature of the CPU increases when making a compressed image. If the CPU, Memory or other vital areas get too hot then the solution is to get better fans.

 

Here are some actual numbers so you can draw whatever conclusion you wish.

One 1.2G AMD machine and one 2.8G Intel machine. All disks 7200rpm and second internal HD used for backup. Automatic Validation at end of archive creation. Temperatures measured by Motherboard Monitor 5.
Archive creation and validation took very roughly 5 min each.

Numbers are: CPU Temp/Chipset Temp in degrees C.

AMD:
Idle 51/35 before normal test and No comp test.
End of Archiving 55/35 Normal compression
End of Archiving 53/35 No compression
End of Validate 55/35 Normal compression
End of Validate 53/35 No compression
Compressed Archive 3.49GB
Uncompressed " 5.35GB or 1.86GB larger

Intel CPU:
Idle 30/29 before normal test, 31/31 before No comp test
End of Archiving 44/31 Normal compression
End of Archiving 37/32 No compression
End of Validate 37/33 Normal compression
End of Validate 33/32 No compression
Compressed Archive 5.07GB
Uncompressed Archive 7.83GB or 2.76GB larger

The reason the Intel machine is cooler to start with and makes the rise look large is because the Intel CPU is capable of "halting" when it is doing nothing. The older AMD CPUs could not do this trick. Of course, the systems fans, components are not the same either.

I did a bunch of operations on a 5MB jpg in Paintshop Pro and was able to raise the Intel CPU temp up to 36C.

The way I see it:
The 2C higher temp when the archive is compressed on the AMD machine is negligible.

The 7C increase on the Intel CPU is more significant but notice that the CPU temperature is only 44C which still 7C under what the AMD runs at when it is idling.

I dismiss the temperature rises as anything to be concerned about. Of course, if your system is running way too hot to start with then you can have a problem but in that case the temperature rises are going to be much larger. Regardless, the root cause is a cooling problem not a compression problem.

Note that in both cases 35% more data was transferred to/from the disk in the uncompressed case. I would be more concerned of a screwup because of the increased disk activity than anything to do with the CPU system handling compression.

My conclusion: Normal compression is a good feature to use.

 

No compression also means that the backup file isn't larger and doesn't take longer to write in certain sitations where compression yields that same or more bytes and the comrpession overhead only adds to the file creation time. Compression isn't always useful.

 

Yes, it depends on the data and I'm guilty of thinking within the confines of how I use TI which is to backup OS and apps only. When I did use TI imaging on a partition that was exclusively jpgs I indeed ran with no compression.

However, if archiving works with no compression and fails with compression, no matter what the data source is, there is a problem with the machine.