Windows XP help - Disk Cleanup

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- - Disk Cleanup (http://www.pcbanter.net/showthread.php?t=1107344)

I occasionally run Windows' Disk Cleanup to purge cruft
left over from updates. I started it today and it reported
that it could liberate 21GB! on C:. The list of files to
delete included an entry I'd never seen befo "Compress
your OS drive" (20GB), but that entry was NOT checked so
would be skipped if I pressed OK. Is Cleanup proposing to
actually compress the drive or is there a hulking file
somewhere that it concludes I don't need?

Jason wrote:
I occasionally run Windows' Disk Cleanup to purge cruft
left over from updates. I started it today and it reported
that it could liberate 21GB! on C:. The list of files to
delete included an entry I'd never seen befo "Compress
your OS drive" (20GB), but that entry was NOT checked so
would be skipped if I pressed OK. Is Cleanup proposing to
actually compress the drive or is there a hulking file
somewhere that it concludes I don't need?

This is my result today.

https://i.postimg.cc/6p4S2Kxm/cleanmgr.gif

The OS has the ability to apply NTFS "new style" compression
to selected files. The "compact" command is used. There
is an attribute that indicates whether the OS is a candidate
for compression, but I can't really be sure they know how
to operate that properly. I specifically select
/CompactOS:never on OS volumes here, forcing Windows to
re-expand the crap it compressed. I even do that on the
SSD drives. CompactOS is not applied to any of your data
partitions, and only applies to C: if/when applicable.

In any case, WinSXS (maybe 6GB of stuff), some of the
files in there may be candidates for compression. I don't
think the intention is to compress System32 "kernel.dll"
or equivalent operational files. I thought the design intent
was to compress "little used" files, and WinSXS has some
of those.

In my example picture, the largest numeric value is related
to my Downloads folder (which happens to be my work
folder and has a Chromium build in it). I have to be
careful not to tick the box for "Downloads" in the picture.

The "Windows Update Cleanup" could be my SoftwareDistribution,
which should really be self-cleaning. I don't plan on
ticking the box on that one either. So let's make a list
of candidates and see how they match up. Hmmm... Not
what i was expecting.

Windows Update Cleanup 3.92GB === proposed cleanup

SoftwareDistribution 321MB (candidate list)
C:\$WINDOWS.~BT approx zero
C:\$WINDOWS.~WS approx zero

C:\Windows\Installer 3.25GB for 1,755 .msi files (MSI is compressed internally)

WinSXS 8.88GB for 63,632 files

It's nice that no combination of candidates equals 3.92GB.
Maybe that's an estimate of the damage they could do to
WinSXS ?

*******

I don't generally recommend selecting any compression option as:

1) Compression is slow.
2) It has the potential to fragment things (at least the
"old" NTFS compression had that capability. I've noticed that
The "write unit" size on Win10 has increased to what could be
64KB, so it's possible they've paved over that problem.
3) Such Compression selections only make sense for 32GB
tablets, where the user is fighting with the OS for space.
And who doesn't want to do more Flash write cycles on
an eMMC chip that requires unsoldering to replace ?
Tablets are the perfect place for beating the **** out
of Flash.

Paul

Jason wrote:
In article , lid says...
1) Compression is slow.

Yes it is, but tweaked lzw compression allows for very fast expansion.
Years ago, IBM added some instructions to the RISC/6000 to perform it.
RISC instructions have less entropy than CISC instructions, so it's a
win.

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Apparently the Compact command has been given four
algorithms, but it doesn't say here which one is
used for the /CompactOS option.

https://winaero.com/blog/ntfs-lzx-co...hm-windows-10/

LZX
XPRESS4K (fastest) (default)
XPRESS8K
XPRESS16K

(LZNT1 is the old compression method as a built-in
LZNT1 uses no Reparse Point per file.)

In Win10, if you issue

compact /compactOS:never

and if the files aren't compressed, it takes forever and
the command returns

0 of 17983 files decompressed

In other words, it takes a while just to check for
Reparse points on all the files. I think it's possibly
the overhead on selecting the files, that makes it slow.

And I've had Cleanmgr.exe spend two or three hours
compressing those files. Whatever method they were using,
there must have been a complicating factor (Windows Defender
scanning each file too?).

The compressor that handles WIMs seems to be in the
same class as 7Z. It takes a while, and the compression
achieved is pretty good. One way to test that, would be
to see if 7Z extreme setting, can make storage of Win10
ISOs smaller.

Paul

On Mon, 11 Feb 2019 22:41:51 -0500, Jason
wrote:

In article , lid says...
1) Compression is slow.

Yes it is, but tweaked lzw compression allows for very fast expansion.
Years ago, IBM added some instructions to the RISC/6000 to perform it.
RISC instructions have less entropy than CISC instructions, so it's a
win.

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This is *not* an e-mail message you sent, it's a newsgroup posting.
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Ken Blake wrote:
On Mon, 11 Feb 2019 22:41:51 -0500, Jason
wrote:

In article , lid says...
1) Compression is slow.

Yes it is, but tweaked lzw compression allows for very fast expansion.
Years ago, IBM added some instructions to the RISC/6000 to perform it.
RISC instructions have less entropy than CISC instructions, so it's a
win.

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

This is *not* an e-mail message you sent, it's a newsgroup posting.
And nobody here or in any other text newsgroup cares that Avast
checked it for viruses. A text-only message can not be infected with a
virus.

Please turn off that ad that Avast puts in your messages. It's nothing
but spam.

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