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Re: jkhv (Sector by Sector Backup)

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Char Jackson <none@none.invalid> wrote in
news:tb6v9f1gc7dmucn69fvlmt7s69rjl5d679@4ax.com: 

> On Tue, 21 Apr 2020 21:00:06 -0400, Paul <nospam@needed.invalid> wrote:
> 
>>Boris wrote:
>>> Why does Acronis True Image, the free Western Digital Edition, have
>>> the option to do partition image backups, sector by sector.  The
>>> default is to have this option disabled, but if enabled, there is a
>>> sub-option to include all unallocated disk space?
>>> 
>>> https://postimg.cc/tsFcLjwd
>>> 
>>> So what does the default setting do?
>>> 
>>> And, I read a while ago that sector by sector eliminates any
>>> compression?  True?
>>> 
>>> Thanks. 
>>
>>Backing up sector by sector, where unallocated are not captured,
>>replaces unallocated with zeros. If the program supports GZIP style
>>compression, the zeros portion compresses to nothing. 20GB of
>>files on a 1TB drive can then be stored in <20GB of space
>>(compressible). Nothing prevents a compressor from compressing any
>>"stream" of data, if that's what you want.
>>
>>           <------ 20GB disk reads, to get this ---------> <- no reads
>>           this part  -> 
>>                                                              (faking
>>                              this part) 
>>                                  LBA
>>           <--------------------------------------------->
>>           sectr|sectr|sectr|sectr|sectr|sectr|sectr|sectr
>>           000000000000000000000000 
>>
>>           <---- compress the whole pattern, including the fake part,
>>           then write --> 
>>                 could be less than 20GB total writes
>>
>>           If image is ever "exported", then the program pretends that
>>           1TB worth of sectors are available.
>>
>>In the case of ticking the "please capture the unallocated", this
>>would also be termed a "forensic copy". It allows a person with
>>an "unerase" program, to flip the byte in the $MFT that marks
>>a file as erased, and set it back to the unerased state, and then
>>the file can be both seen and read. The pattern in this case, looks as
>>follows. The compressor can run if it wants. *But*, because
>>the unallocated is not just random stuff pulled off the disk, the
>>20GB of files stored on the 1TB drive now takes 400GB of (compressed)
>>storage. The compression is lossless, and probably isn't all that
>>compressible. 
>>
>>           <----------- disk reads for the whole thing
>>           ------------------------------> 
>>
>>                                  LBA
>>           <--------------------------------------------->
>>           sectr|sectr|sectr|sectr|sectr|sectr|sectr|sectr
>>           13572468ACEFBD0045671234... 
>>
>>           <---- compress everything, write it out compressed
>>           -----------------------> 
>>                 pattern might not be very compressible
>>
>>If you're the kind of person who zeros your drives before first
>>usage, even when you tick the "capture unallocated" option, the
>>output may still have a significant number of zeroed LBAs and
>>it compresses nicely.
>>
>>Find a small disk, and you should be able to verify these
>>behaviors a bit faster. I don't know what the Acronis
>>export options are, or how easy it is to verify what
>>got captured.
>>
>>The smallest WD disk I've got is 4GB :-) It has a piss poor
>>read/write rate. But it might be good enough to fool the
>>Acronis branding check that it's a WD disk. The slowness of the
>>disk, negates the small size, so it's not particularly
>>attractive to hook to the computer in 2020.
> 
> It's worth reminding folks who have a branded version of Acronis True
> Image that as long as any drive in the system is a qualified drive, then
> every drive is included under the umbrella.
> 
> So for example, if you're trying to back up a Seagate drive, you can do
> that with a WD-branded ATI as long as you have at least one WD drive
> connected.
> 

Yes, pretty loose requirements to use ATI WD Free.  

If you purchase a WD My Book, WD Essentials, or My Passport external hard
drive, included is WD's own WD Backup software, and other WD tools. I've
use the software and browsed the tools.  The WD Backup software is very
limited, and somewhat confusing.  I do find WE support, email and phone,
quite good. 

I use Macrium Reflect Free, too.  With Macrium Free, you can't preview a
file (pdf, xlsx, docx, jpg, etc) by browsing with Windows Explorer, you
have to launch Macrium and create a virtual drive first, whereas with
Acronis, you can preview a file and see it's innards.  With both you can
open files, edit, and save to original location.  With Macrium, you do it
from the virtual drive, and with Acronis, you do it from Windows Explorer
("Open with..."). 

Of course, you know all this.

I've only cloned with Macrium (AOMEI).

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Thread

jkhv Boris <nospam@nospam.invalid> - 2020-04-22 00:29 +0000
  Re: jkhv Paul <nospam@needed.invalid> - 2020-04-21 21:00 -0400
    Re: jkhv Char Jackson <none@none.invalid> - 2020-04-21 20:14 -0500
      Re: jkhv (Sector by Sector Backup) Boris <nospam@nospam.invalid> - 2020-04-22 03:00 +0000
        Re: jkhv (Sector by Sector Backup) Boris <nospam@nospam.invalid> - 2020-04-22 20:18 +0000
    Re: jkhv (Sector by Sector Backup) Boris <nospam@nospam.invalid> - 2020-04-22 02:30 +0000
      Re: jkhv (Sector by Sector Backup) Paul <nospam@needed.invalid> - 2020-04-22 02:08 -0400
        Re: jkhv (Sector by Sector Backup) Boris <nospam@nospam.invalid> - 2020-04-23 03:09 +0000
          Re: jkhv (Sector by Sector Backup) Paul <nospam@needed.invalid> - 2020-04-22 23:34 -0400

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