Fat32 partition size / cluster size question

M

Mike S.

Hi,

Using Partition Magic, I want to partition my disk before installing XP.

I know that the maximum partition size is related to the cluster size, but
I'm wondering if the maximum *is* allowed.

For example, if I'm using 8K clusters, is the maximum partition size 16.00Gb
(16 777 216Kb) or just below that mark ?

I know that Win98 "scandisk" gives an error message if the cluster size is
incompatible with the partition size, but I did not found where XP checks
and reports this.

TIA !
 
R

Rick \Nutcase\ Rogers

Hi Mike,

It still matters, you should stick to the default sizes. The problem has to
do with the maximum amount of entries in the file allocation table. You will
find it described in more detail on this link from MVP Ron Martell:
http://onlinehelp.bc.ca/tips.htm#scandisk

--
Best of Luck,

Rick Rogers, aka "Nutcase" - Microsoft MVP

Associate Expert - WindowsXP Expert Zone

Windows help - www.rickrogers.org
 
G

Gerry Cornell

Rick

Am I mistaken? The link you have provided deals with the timidities
provided with Windows 98. I thought new utilities come with Windows XP!

--


Regards.

Gerry

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G

Gerry Cornell

Mike

How large is the hard disk? Is Windows XP to be the only operating
system i.e. you are not planning to dual boot? If only Windows XP have
you considered NTFS?

--


Hope this helps.

Gerry
~~~~~~~~~~~~~~~~~~~~~~~~
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Stourport, Worcs, England
Enquire, plan and execute.
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Please tell the newsgroup how any
suggested solution worked for you.



~~~~~~~~~~~~~~~~~~~~~~~~
 
M

Mike S.

Thank you both for the provided information.

It is still unclear to me, since the documents do not say all the same
thing.

In Rick's reference, it says:

Up to 8 gb -> 4K clusters
8 to 16 gb -> 8K clusters
16 to 32 gb -> 16K clusters
32 to 64 gb -> 32K clusters

-> For "exactly" 8Gb, do I use 4K clusters ? 8K clusters ? Doesn't
matter ?


In the MS document referred by BAR, it seems that the upper limit is not
included:

Partition Cluster
512 MB to 8,191 MB --> 4 KB
8,192 MB to 16,383 MB --> 8 KB
16,384 MB to 32,767 MB --> 16 KB
Larger than 32,768 MB --> 32 KB

--> in that case, it looks like the upper limit for a 4K cluster size is
7.99Gb (8192 - 1 Mb)


But in that other MS document, it says the opposite :

http://www.microsoft.com/resources/documentation/Windows/XP/all/reskit/en-us/prkc_fil_lxty.asp

If you look at the smaller partition sizes, it looks like the "rounded"
number is allowed as the upper limit (ex: 1024Mb) while the lower limit of
the next step is that number plus 1 (1025Mb)... This is less clear at the
8GB level, but on can infere that 8Gb is the upper limit of the 4k cluster
while the lower limit of 8k clusters is 8.01Gb..


To make things worse, Partition Magic (8.0) doesn't seems to be in
accordance with XP.

For example, if I create a 8202.3Mb partition in PM with 4K clusters, (total
size of 8,600,707,584 bytes), and then use chkdsk on that partition in XP,
it reports a number of 2,095,684 4K clusters, or 8,583,921,664 bytes, which
is 8,186.26Gb. Go figure !


In that case, am I within the 8191 / 8192 size limit according to XP or over
the limit according to Partition magic ??


I know the safest thing would be to use a number below 8192 in partition
magic, but I'd like to know how high I can safely go in XP.

TIA..
 
M

Mike S.

Gerry,

It is a 40Gb hard disk. But AFAIK, size doesn't really matter. I'm just
trying to understand well how to safely deal with these size limits.

And yes, I plan to make it a dual boot system; that's why I stick with FAT32
for the partition that will contain the data accessible from both o/s. (For
both, the "My documents" / "Documents and settings" folders will be on the
common drive).

Thanks
Mike
 
R

Rick \Nutcase\ Rogers

Hi Gerry,

It does, but that doesn't change the logistics of the file system.

--
Best of Luck,

Rick Rogers, aka "Nutcase" - Microsoft MVP

Associate Expert - WindowsXP Expert Zone

Windows help - www.rickrogers.org
 
J

James Hahn

For exactly 8Gb it's 8K clusters, but you would never build a partition like
that because you are getting the disadvantage of the larger cluster size
without the benefit of the larger partition size. Go for the largest
partition under 8Gb that allows 4k clusters.
 
M

Mike S.

Thanks James..

That's exactly what I want to do.. My question was wether the upper limit
was "included" or not, since the docs I read it were unclear.

My partition is now at 7.99 Gb.
 
C

cquirke (MVP Win9x)

Cutting to the chase, the limits I suse (for 7.99G FAT32 with 4k
clusters) are 8181M in BING, which yeilds 8174M in today's large HDs
(as the rounding granularity shifts). With low rounding granularity
on smaller HDs, 8189M seems to be the max.

Then I check to see if I have the 4k cluster size I want and scale
down if not. The limit values (512M, 1G, 8G etc.) are always the
first point at which the larger cluster size starts to be used, so you
typically want to be just under that.


---------------- ----- ---- --- -- - - - -
Cats have 9 lives, which makes them
ideal for experimentation!
 
C

cquirke (MVP Win9x)

On Sat, 19 Feb 2005 16:05:21 -0000, "Gerry Cornell"
Am I mistaken? The link you have provided deals with the timidities
provided with Windows 98.

File system structure is file system structure, irrespective of the
tools used on it. A tool that "breaks the rules" is dangerous,
because it goes out of compatibility with other tools and sows the
seeds for data corruption later.

The limits are cast in 16-bit stone for FAT16, but are conventions to
be ignored at your peril in FAT32. IOW, you physically cannot create
a FAT16 volume with more clusters than the 16-bit FAT can address
(though you may be able to force larger clusters with smaller FAT).
You may be able to force FAT32 to use smaller clusters on larger
volumes, resulting in larger FAT that can nevertheless still be
addressed by 32-bit addressing, but generally you would avoid this.
I thought new utilities come with Windows XP!

To be brutally hosnest, the tools that come with XP border on the
incompitent, where FATxx is concerned.

The partitioner is broken, in that while it tries to create FAT32
volumes > 32G, the process fails, leaving whatever was there destroyed
and no useable volume or partition because the volume is "too big".
Other tools can create FAT32 patritions and volumes as large as you
like; if there's a limit, I haven't hit it (up to 200G so far).

The disk maintenance tools suck rocks, for NTFS and FATxx alike.

Instead of the interactive (as in "no, I don't care if you think the
distant half of C:\WINDOWS is corrupt, DON'T truncate it") Scandisk,
you are forced to use DOS 5 era ChkDsk /F that blindly fixes without
prompting permission first.

AutoChk (which runs automatically after bad exits) is worse; there's
no "look, don't touch" mode at all - the *only* way it can work is in
kill, bury, deny mode (i.e. irreversably and often destructively "fix"
things, hide the details deep in Event Viewer where only a living OS
has any chance of ever seeing again).

All of this gets worse in FATxx, because the normal disk-checking UI
(rt-click, Properties, Tools, etc.) runs so quickly in FATxx volumes
that I doubt if it really checks anything at all. As it is, it seems
as if ChkDksk doesn't spot or fix invalid file names (i.e. those wierd
names that nothing can delete), which forces the FATxx user to
Scandisk from DOS mode and the NTFS user to... well, give up?

No-one's had their eye on the ball where these things are concerned,
and it shows. Most of us - myself included - worry more about malware
attack, and tend to forget about the natural risks to data.

--------------- ----- ---- --- -- - - -
Never turn your back on an installer program
 
M

Mike S.

The limit values (512M, 1G, 8G etc.) are always the
first point at which the larger cluster size starts to be used, so you
typically want to be just under that.

Thanks, that answers my first question.

My second one is: *which* figure should be "just under that": the whole
partition size (including the FAT) or the resulting free disk space ? Let
me explain:

In Partition Magic, if I set the partition size required to 8191Mb, PM
"rounds" (!?) that number to 8194.9Mb, showing that 16Mb are "in use",
leaving 8178.9 Mb free. (I guess the 16Mb is used by the FAT32 pointers ?)

Once formatted, the disk is reported as: 8,178.9Mb total space, (2,093,797
* 4kb clusters.) or 7.987Gb

Upon install, XP shows the partition as 8195Mb Total, 8179Mb Free, and once
the installation is finished, "My Computer" shows the drive as a 7.99Gb
total size.

With all these specs, am I over or under the 8Gb limit ??

Thanks
 
J

James Hahn

PM implements the MS standard by default, so if you have 4K clusters you are
under the magic figure.
--
 
M

Mike S.

Thanks, I found that it is true when you create a new partition.

There only seems to be a problem when you change (move/resize) an existing
partition and that change cross a size limit: PM doesn't change the cluster
size and it won't warn you either that the new partition size/cluster size
are no longer within the MS standards..

That explains some of the problems I experienced before !

I Think I can call this case closed now..

Thanks again to all who helped !
Mike
 
C

cquirke (MVP Win9x)

There only seems to be a problem when you change (move/resize) an existing
partition and that change cross a size limit: PM doesn't change the cluster
size and it won't warn you either that the new partition size/cluster size
are no longer within the MS standards..

BING gets that right, and that's enough reason (yes, there are others,
such as price) to chuck PM and use BING instead.


---------------- ----- ---- --- -- - - - -
Cats have 9 lives, which makes them
ideal for experimentation!
 

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