Mb per block: vista NTFS format?

[Guest]

Hello,

I have a Toshiba laptop with Vista. I had a shrink problem with the default
partition size. I downloaded PerfectDisk to defrag and used BootIt NG to do
the job. I noticed then that when using the defrag tool, it told me that the
partition (C had : 21.23 Mb per block

I had a problem with a dual boot and other OS installation. I had to use the
Toshiba rescue disk to get back to the factory installation... since then,
when using the same defrag tool, is now indicating : 11.57 Mb per block !!!

Does this mean that for the same block on HD, I can now write almost half
the Mb then before???? Is this a good understanding? So, for the same picture
file of 3Mb, I will use twice the space on HD then before?

If so, how can I change this? I notice that my D: partition formated by
Vista has 16Mb per block... why this differnece between the 2 partitions?

I hope someone can explain this Mb per block value! And how to get the most
out of the HD space.

Thanks!

 

[Chris Heald]

Each file must consume at least one block. If you have small files, they
will still use one block so 3mb file will now take 11.57mb space instead of
21.23mb.
Smaller blocks are better.

HTH
Chris

 

[Guest]

Each file must consume at least one block. If you have small files, they
will still use one block so 3mb file will now take 11.57mb space instead of
21.23mb.
Smaller blocks are better.

HTH
Chris

Hello Chris,
Thanks

1) I guess the format tool has set this value? I used BootIt NG to resize
and and format both C: and D: This tool did not offer to set Mb per block...
and still C: now is around 11Mb per block and D: is around 16. How I can
understand this?

2) If my 3Mb file is using 1 block, this meens that in a 11Mb block, I just
loss 8Mb of space available!!! This is huge. ?

3) What is the normal Mb per block? If the Toshiba factory setting gave me
21Mb per block, this seems crazy! Very few files on a disk will be more than
11 Mb to use the entire block. How can I optimize?

Thank you very much!

 

[cquirke (MVP Windows shell/user)]

"Chris Heald" wrote:

Not always, no - there's a downside to too many clusters (especially
in FAT32) and reasons to avoid non-standard cluster sizes. There's
also a particular efficiency when paging to disk, in that the
processor's natural page size is 4k.

1) I guess the format tool has set this value? I used BootIt NG to resize
and and format both C: and D: This tool did not offer to set Mb per block...
and still C: now is around 11Mb per block and D: is around 16. How I can
understand this?

It won't be "11M" (or any M) per block, if by "block" you mean
"cluster", as opposed to arbitrary display blocks in DOS mode Scandisk
surface scan and similar 3rd-party tools.

Cluster sizes are a power of 2 x sectors, from 1 sector (512 bytes) up
to 128 sectors (64k, or 0.064M) for NT-only FAT16 volumes 2-4G in
size. Usual sizes are 4k (mist NTFS, FAT32 up to 8G), 8k, 16k or 32k.

2) If my 3Mb file is using 1 block, this meens that in a 11Mb block, I just
loss 8Mb of space available!!! This is huge. ?

Clusters are smaller. A file that is exactly 3M will be = 3072k; as
all clusters divide into 1M evenly, it will take the same space. But
if 1 byte over exactly 3M, the "waste" will be between 511 bytes and
65534 bytes (nearly 64k) at worst.

The problem is more pronounced with small files, e.g. under 1k in
size. A collection of 1000 such files may be only 1M or so of data,
but could occupy up to 64M, worst-case.

In practice, the impact isn't that huge - well within the margin of
free space you need to defrag, for example. As a huge number of
clusters means more fragmentation and far more tedious defrag process,
being able to cram up a volume by "saving space" with small clusters
is just going to give you a different kind of problem.

3) What is the normal Mb per block? If the Toshiba factory setting gave me
21Mb per block, this seems crazy! Very few files on a disk will be more than
11 Mb to use the entire block. How can I optimize?

What is the context of these "blocks"? Is it:
- clusters, as we've assumed?
- some sort of diagnostic display?
- IDE block writes in CMOS setup?

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[Guest]

:

What is the context of these "blocks"? Is it:
- clusters, as we've assumed?
- some sort of diagnostic display?
- IDE block writes in CMOS setup?

Hello,

Thanks. I really dont know... I have seens this in the PerfectDisk defrag
tool I used. When you clik on a drive and ask for defrag or statistics, you
see in the upper right coner:
Megabytes per block : 11.38 for example.

Since I saw for sure 21 with the laptop's firts boot and a totally different
value after having resized the partitions and used the CD restore to put back
Vista, thats why I was warried.

Can Windows Vista tell use what are the current amount of sectors in the
clusters or block?

Thanks!

 

[cquirke (MVP Windows shell/user)]

"cquirke (MVP Windows shell/user)" wrote:

Thanks. I really dont know... I have seens this in the PerfectDisk defrag
tool I used. When you clik on a drive and ask for defrag or statistics, you
see in the upper right coner:
Megabytes per block : 11.38 for example.

Ahhh...

That's not cluster size, or in fact anything that matters - that's
just how the "disk map" display is presenting its info to you.
There's no "real" unit that size in the file system.

Various tools that operate on disk volumes may show you a "map" of how
the space is used across the volume space, or just how the test is
progressing across this space (e.g. HD Tune).

Some maps show the whole volume space at once, dividing this into as
many blocks as the screen space and/or character resolution allow.
Examples include DOS mode Scandisk, old DOS-era Defrag, HD Tune, and
some other 3rd-party tools such as yours.

Other maps show a 1:1 relationship between clusters and "blocks", even
if that means the display has to be scrolled because there are too
many clusters to map on screen. This is how Win9x Defrag works.

Some tools don't show any map at all (e.g. Win9x Scandisk surface
scan, NT ChkDsk) or even progress (Vista's Defrag - the new nadir)

In your case, your "blocks" are just the number of clusters that are
shown as a single map block. If you resize the app's window, you may
see the block size vary. It has nothing to do with clusters or file
system - it's purely a display convention particular to that tool.

Can Windows Vista tell use what are the current amount of sectors in the
clusters or block?

Yes I think so, or you can deduce it by creating a file with a single
character in it and seeing how much space (one cluster) it occupies.

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