Hi
02 Dec 2000, "L.D. Best" <[EMAIL PROTECTED]> wrote:
>> ??? sector size _IS_ 512 bytes !!
>> M$ does not use large sectors (who has told you so ??)
LB> You did ...
nope ... :)
LB> or so it appeared in the message I was responding to:
FAT groups sectors together to form clusters.
And FAT32 does not use larger clusters (it uses SMALLER clusters as an
equally large FAT16 partition), but it can use _MORE_ clusters.
FAT 16 can use at most 2^16 (=65535) clusters ... hence the name FAT_16_
FAT32 can use at most ... you guessed it ... 2^32 ;)
LB> And, according to the software I have [called DOS] this
>> LB> Would someone explain to me please how cluster/sector size on a
>> LB> HDD has any effect on RAM usage?
>> sector size not ... it's usually 512 bytes.
LB> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ isn't true. I have my
LB> RAM drive set with 512 sectors, but my HDD has sector size 2048 on the
LB> primary drive, and temporarily 30K on the 2nd HDD.
these are CLUSTERS
FAT groups together sectors and forms clusters.
So you have to administer less units.
a clustersize of 8KB means that a cluster consists of 16 512 byte clusters.
>> CLuster size yes ...
>> you have to store the FAT in RAM ...
>> with FAT16 there are at most 65535 clusters ....
LB> How is this computed, and what determines cluster size?
the fact that determins size is that there have to be less than 65535 on
fat16.
When you format a partition format looks at the minimum cluster size it can
get away with ... (eg 1.8 GB ... format recognizes that it has to use 32 KB
clusters (64 sectors) in order to have less than 2^16 clusters)
>> with FAT32 there are a LOT more ... these take up additional space.
LB> Same questions.
here it is more subtile ...
I don't know exactly ... because here you have to make a tradeoff between
clustersize and administerability (??).
smaller clusters have less 'slack' space, but they take up more RAM to
administer.
>> LB> Thus 1Mb SDRAM can only store x number of sectors even if those
>> LB> sectors don't add up to anywhere near 1 MegaBYTES of
>> LB> datapoints??
>> ??? I don't see the point
LB> You say that FAT32 takes up more RAM if "allocation unit" is
LB> smaller.
DOS has to know the layout of the clusters.
If there are more of them, than DOS has to use more memory to store that
information.
Imagine clusters sizes of 1 KB and 8 KB.
1 KB clusters have less slackspace, but you need 8 times the memory that
would be needed if you would have used 8 KB clusters.
LB> The only way that could be true would be if said "allocation unit"
LB> were smaller than the smallest memory segment of a RAM chip...
you think too complicated :)
LB> i.e. the only way the same amount of data in FAT32 v FAT16 would take
LB> more space in RAM for FAT32 would be if FAT32 somehow produced
LB> "slack" in RAM.
no ... there is no slack in ram, and the smallest memory allocation unit is
1 byte.
HDD: (16 sectors - is 512 bytes)
FAT16 (f - cluster size of 8 KB)
FAT32 (3 - clustersize 1 KB)
----------------
f
3 3 3 3 3 3 3 3
which one produces more slack, and which one uses more memory to store
administrative information ??
fat32 can use smaller clusters, because it can potentially administer MUCH
more clusters (2^32 versus 2^16)
>> RAM stores bytes, and HDD as well ...
>> on HDD there can be slack space ... because data is allocated in x
>> bytes chunks.
LB> According to what's been written, that's not the case.
LB> You clearly stated that FAT32 would eat up more RAM ...
you mix things together ... see above
>> The discussion is about FAT32 ...
>> there can be more clusters, so you can have larger HDDs, and usually
>> SMALLER clusters ...
>> But performance degrades ...
LB> WHY?
see above
LB> Everything you said this time around supported my stance that RAM
LB> stores by byte, yet you're saying cluster size determines RAM usage.
it determins ram usage for administering the filesystem
LB> WHY? If I have 1Mb of data in my FAT16 table, or 1Mb of data in a
LB> FAT32 table, how can cluster size affect amount of RAM used???
you want to format a 1.2 GB harddisk (as 1 partition)
FAT16 uses 39.322 32 KB clusters
fat32 can use eg 39.322*8 4 KB clusters.
partition size is the same, but fat 32 with 4 KB clusters uses 8 times the
RAM that would be needed with fat16.
clear ?
LB> l.d.
CU, Ricsi
--
Richard Menedetter <[EMAIL PROTECTED]> [ICQ: 7659421] {RSA-PGP Key avail.}
-=> Why did the Mafia kill Einstein? - He knew too much <=-
