From: nospam@needed.invalid   
      
   On Thu, 2/12/2026 2:26 PM, Carlos E. R. wrote:   
   > On 2026-02-12 17:34, Paul wrote:   
   >> On Thu, 2/12/2026 7:06 AM, micky wrote:   
   >   
   >   
   >> Backups can be compressed. To do this, I recommend "no compression at all"   
   >> when making the original backup, so that one very good compressor does the   
   job   
   >> when you are compressing the file. Compression takes a long time, unless   
   >> you had prepared in advance with a Big Machine :-) The Big Machine does   
   >> ultra compression at 50MB/sec. Which means you have to be "Very Patient"   
   >> when waiting for it to finish. My partition full of ISOs, it does not   
   >> compress at all. It's a total waste of time to compress that one. Whereas   
   >> my partition full of iambic pentameter (poetry), that compresses very well.   
   >   
   > Fast compression is almost as fast as the hard disk, say 150 MB/S. It may   
   not be worth it to use high compression.   
   >   
   > If you are using NTFS, you can simply mark a directory as compressed,   
   > and write everything to it. It should be fast. I don't remember if you   
   > can adjust compression ratio.   
   >   
   > On Linux, the only filesystem that does r/w transparent compression is btrfs.   
   > Others announced it but never implemented it (ext3).   
      
   7Z Ultra is about the best compression you can get, but it's expensive.   
      
   7Z also has a Fast, which is fast, and can achieve quite high rates.   
   It is useful for some purposes. It's even possible that isn't an   
   arithmetic compressor (to get that kind of speed).   
      
   The trashy compressions, the LZ4-quality methods, IDK, those are   
   just a crazy choice. They can save something, but the cost is   
   way too high for the effort. If you're going to do a thing,   
   do it once and do it right. There are lots of situations where   
   the really bad compressors only save 1%, and then the operator   
   will have a scowl on their face. My partition full of downloaded   
   ISO files, that doesn't compress at all.   
      
   When you compress a material, you should not compress a compressed thing.   
   Switching on (default) Macrium "medium" compression followed by 7Z Ultra,   
   does not give the best result. You would set Macrium to "none" and   
   then do your 7Z Ultra. There is even a claim, that 7Z on eight cores   
   does not make as compact an archive as 7Z on two cores or one core sort   
   of thing, but I haven't spent the time to compare them.   
      
   This is a taste thing. Salt to taste.   
      
   This is never going to save a lot of space. But if you have a 1TB   
   Macrium file in front of you, it will make the space you need to   
   save a few picture files. And you still need the "space to work" to   
   do this. A 1TB file needs a 1TB hole, to attempt the compression.   
   (Then you delete the original and are left with a 1.3TB hole,   
   you have "gained" from the process.) You can sometimes see early   
   in a compression, that the meter reads "80%" and maybe you're not   
   getting enough compression to be bothered to finish the run and   
   you can abort it. But some compression runs, if it says "30%",   
   then you stand to make a significant saving by carrying this out.   
      
      Paul   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)