Cluster size for memory card

[alexredfeet]

I saw many posts about the cluster size and formatting for the memory cards but not one person who said what size the cluster should be. I put my new 2gb SanDisk Memory card into the mem card reader and connected it to my pc and it said i should format it.
I formatted it as FAt32 and cluster size 32 bytes ( i think ).
However when i formatted my 1gb card it recommended i format it as size 16.

I wonder if someone can commment on what type of formatting the disk should be done as for my N95.

Thanks

[Gizmoratty]

If you want to be safe, always format memory cards from the phone itself

That way you can never blame yourself for getting it wrong ;P

Menu -> Tools -> Memory -> Options -> Format Memory Card

[alexredfeet]

however.... Apart from formatting on the phone. What is the best cluster size when formatting with the pc. And could someone comment on the differences as in relation to the specifics above.

[AngusG]

Originally Posted by alexredfeet

however.... Apart from formatting on the phone. What is the best cluster size when formatting with the pc. And could someone comment on the differences as in relation to the specifics above.

cluster size - Google Search

FAT32's your best bet... I think I read somewhere that by default the phone will format 4 GB cards as FAT32 but anything less as FAT16... guess it must be the SHDC...

[alexredfeet]

I understand it should be FAT32, and that was set as default. However my point and question was what allocation unit size to be specific. ?
A it gave me the option of choosing 4 bytes, 8 bytes.... and so on.
However i was not sure which it should be? or which is best suited for the 2gb card when used in the n95.?

As mentioned above, before formatting the 1gb card it had a lower default allocation size. But perhaps the 2gb card is best suited for a lower byte size too.

[Homer]

Originally Posted by Gizmoratty

If you want to be safe, always format memory cards from the phone itself

That way you can never blame yourself for getting it wrong ;P

If you do that with a 2Gig card and use Maps then you will lose around 100MB due to the phone using FAT16

IRT the author of this thread. Windows (assuming that's what you used) defaults to the smallest cluster size and this is what you want unless you know you will be only using the card for large files.

Larger cluster size means more potentially wasted space.

[Tizbad2k]

The last poster knows a bit about what he is commenting on. I on the other hand have absolutely no idea whatsoever about this application, but do have some formal education on computer architectures.

The cluster size issue is something you shouldnt spend too much time worrying about, because its likely the phone will use the optimum size for its intended application.

With todays modern systems, 8/16 bit/byte (cant recall, its likely to be bit) cluster sizes really become an issue when considering backwards compatibility, this is not to say that there are no performance issues involved, there certainly are, but its likely that this will not be the bottleneck in whatever application you are using it for. One potential issue, in the case that the phone does not know the correct choice, is that you could lose half of your available space because the phone cannot address it (if you chose 16 and the phone only understood 8), I do remember reading about this somewhere but I cant recall if it was in the context of the N95 though.

Hope I didnt confuse you, and Im sorry I couldnt give you the definitive answer that you were looking for.

[Homer]

The problem with using too large a cluster size is that the smallest physical space a file can occupy is one cluster.

Maps on the N95 creates hundreds of files 1k or less in size.

FAT16 on a 2GB memory card will use a 64KB cluster so each of those 1k files will waste 63k
FAT32 will use a 4k cluster size therefore each of those 1k files will use only 4k on the card, only wasting 3k and saving 60k over FAT32.

Since the N95 supports FAT32 it makes sense to use that on all cards over 256MB

[Tizbad2k]

Originally Posted by Homer

The problem with using too large a cluster size is that the smallest physical space a file can occupy is one cluster.

Maps on the N95 creates hundreds of files 1k or less in size.

FAT16 on a 2GB memory card will use a 64KB cluster so each of those 1k files will waste 63k
FAT32 will use a 4k cluster size therefore each of those 1k files will use only 4k on the card, only wasting 3k and saving 60k over FAT32.

Since the N95 supports FAT32 it makes sense to use that on all cards over 256MB

I dont know if what you are saying is accurate, it sounds like it could be, if it is here is a really shocking example of its implications, (just an extension of what you said).

lets say you have 1000 files which have 1k of data each.
best case scenario you use 1 Meg to store them all.

worst case - each 64k cluster only holds 1k, leading to 64Megs required to store of which 63 Megs is wasted. 98.4% Waste

other case - it requires 4Megs to store, in which case you have 3Megs of wasted space. 75% Waste

Shocking!! isnt it?

Which is why I would hope that modern systems would have moved beyond this ridiculous issue by now. But Im an electrical engineer, not computer, so really I cannot be the final word on this type of an issue.

[Tizbad2k]

Ok so to explore the issue a bit further I performed some experiments.

Here is how it started off:

My computer- NTFS >70GB (4kB cluster size)
1byte file -> 4kB size on disk

Kingston 1GB MicroSd Original Format FAT
1byte file -> 16kB on disk

Original Nokia 1GB MicroSD FAT
1byte file -> 16kB on disk

Ok so then I tried formatting the kingston card to ntfs using various cluster sizes ranging from 512bytes to 4kB. And then I got really confused:
Surprisingly in all cases windows explorer reported the file as 1kB , hovering the mouse over the file reported its size as 1B, but right click reported the file as 16kB. And the phone complained that the card was corrupted.

Then I jumped through a bunch of loopholes to get the computer to format the card as FAT32 with 1kB and 512B cluster sizes. Phone accepted the card in both cases, but again windows reported the file size as 1Kb, 1B, and 16kB, depending on which method i used to check size. And the phone reported it as 1B.
However chkdsk at the command prompt reported the file size as 1kB and 512B, respectively.

So to double check this new development I reformatted the card to FAT on the phone, this time the same 1B file was again reported as 1B on the phone and 1kB/1B/16kB by windows, and 16kB by the command prompt.

So the conclusion of this saturday evening foray in the world of file systems and cluster sizes?

Phone accepts only FAT and FAT32 fs, with 16kB as the default cluster size for FAT, and, 512B and 1kB as acceptable cluster sizes for FAT32.

for a 1B file (1Byte=8bits).
In all Cases phone reported file size as 1B
In all Cases windows explorer reported file size as 1kB/1B/16kB.
In the case of FAT32 fs, w/ 512B cluster size, chkdsk reported size on disk of 512B
In the case of FAT32 fs, w/ 1kB cluster size, chkdsk reported size on disk of 1kB
In the case of FAT fs w/ 16kB cluster size, chkdsk reported s.o.d of 16kB

I would trust chkdsk, and and ignore both the phones explorer, and windows explorer, including hovering as well as the right click onto properties on windows explorer.

Result-> all my Microsd cards will now be FAT32 with 1kB cluster size.
(this will hopefully be a good compromise between efficient use of memory density versus excessive fragmentation)

Keep in mind that although I did relatively thorough tests for a tiny 1B file, I have no Idea how things like the camera and other applications will react to the smaller cluster sizes. So reserve judgment till you feel you have enough information.