Is fragmentation an issue on storage cards?

MickH · Occasional Visitor Joined: Dec 23, 2003 Posts: 22

Hi there,

I have seen several posts that refer to defrag utilities for CF and SD cards.
Is there any benefit in using these?

I know that standard hard drives (so presumably micro drives) benefit from unfragmented files because of the reduced amount of physical head travel required for read/write seeks. But seeing as storage cards have no mechanical moving parts, is fragmentation an issue?
Hmm...I can't recall ever seeing a system RAM defragger. Confused

So...Are storage card defrag utilities a genuinely useful asset or just a cynical money maker that takes advantage of peoples fear and ignorance?

Any experts out there know the answer?

Cheers,
Mick.

Dave · Posted: Thu Jan 15, 2004 2:18 pm Post subject:

http://www.softwinter.com/storagetools.html

Some storage cards do have moving parts because they are mini hard drives. But, just because a storage card isn't a hard drive, don't think it doesn't get fragmented. Fragmentation is all about how the card is formatted, and how that type of format utilises and writes data. Storage cards use the same file systems as seen under Dos, Windows 3.1, Windows 95, Windows 98 and Windows ME, so you will still get fragmentation.

A system RAM defragger is basically called hitting the soft reset button. There's no call for one.

MickH · Occasional Visitor Joined: Dec 23, 2003 Posts: 22

Thanks for your response Dave.

I appreciate that storage cards use standard file systems and that fragmentation does occur in these file systems. My question was more to do with the different hardware implementations and the way that data is accessed on solid state devices compared to disk drives and whether or not fragmentation is actually an issue on flash cards.

On disk drives fragmentation impedes performance because there's a variable seek time, depending on the distance the head needs to move, and how much the disk needs to rotate before the required sector can be accessed. Data access is also faster when the sectors occupy outer edges of the disk. Disks are faster when the sectors are arranged without fragmentation to minimize the seek time, and a fragmented disk is slow because the head spends a lot of time travelling back and forth all over the place.
In contrast, flash memory access is completely independent of the actual sector address. There is no head to move back and forth. The addressing is all done electronically, so accessing different sectors on a flash card would take the same amount of time regardless of the actual location on the card. It doesn't matter whether the sectors of a particular file are contiguous or not.

I'm still not convinced that fragmentation on a flash card is an issue.

Rgds,
Mick.

Dave · Posted: Fri Jan 16, 2004 2:14 pm Post subject:

MickH · Occasional Visitor Joined: Dec 23, 2003 Posts: 22

OK. I think I get it now.

My understanding was that each entry in the FAT table contained a reference to the next required sector (i.e. a linked list), until an EndOfFile marker was found, so when accessing files I presumed that once the initial sector of the file had been determined via the file manager, the IO routine would traverse through the FAT creating a list of the required sectors. So accessing a file occupying sectors {895, 2045, 6032, 458} would take the same time as accessing a file in (895, 896, 897,898}.

I didn't realise that whole sections of the FAT were read at a time.

Thanks for the info.
I'll check out the SoftWinter app.

Rgds,
Mick.

Robin2 · Posted: Fri Jan 16, 2004 8:25 pm Post subject:

I found that if I put the storage card in a card reader connected to my PC, my pc's defrag program (Executive software Diskeeper) will defrag the card in a few seconds.
Robin

DavidW · Posted: Mon Jan 19, 2004 1:07 am Post subject:

I find Diskeeper doesn't behave that sensibly on storage cards, particularly those with not much full space. There again, I last tried with Diskeeper 7.0 build 430. I've upgraded to Diskeeper 8.0 Professional yesterday (and installed the patch to move to the very the latest 8.0 build), so I could try again and see if version 8 behaves any more sensibly.

I recommend Diskeeper highly for hard disks. It is certainly a fallacy that NTFS partitions aren't affected by fragmentation. I believe my investment in a very high end HD system in my workstation would be wasted without it. It seems silly to go to the expense of a PCI-X U320 SCSI controller and two Seagate Cheetah 15K.3 U320 SCSI hard disks, then refuse to spend 30 pounds or so for efficient automatic defragmentation. That said, Diskeeper makes just as much sense for people with regular hard disks in their computers.

Just make sure that you buy the right edition of Diskeeper 8.0. With 7.0, if you weren't on a system where Diskeeper was remote controlled from an administrative setup, you could install the cheap Diskeeper Home edition. With 8.0, that isn't always the case - if you use Windows XP Professional, you need Diskeeper Professional (which replaces the old Diskeeper Workstation edition).

Like Dave, I have SoftWinter's StorageTools on my iPAQ. However, though I haven't yet really played with the defragmentation utility, I have a copy of Anton Tomov's Pocket Mechanic - and that looks, if anything, to be a better buy - it does more for similar money. However, StorageTools is a solid offering and I wouldn't want to dissuade anyone from using it.

Storage card performance is definitely hit by fragmentation - comparisons to RAM are invalid, as the read speed of a storage card is much lower than the read speed of RAM.

David

Skippy · Posted: Mon Jan 19, 2004 1:26 pm Post subject:

DavidW · Posted: Mon Jan 19, 2004 10:58 pm Post subject:

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