EXT2 or FAT32

Niraj Kulkarni · 07-01-2009, 08:05 AM

Hi,
I am using FAT32 formated pen drive/HDD on Linux 2.4.
Now I need to store more than 32GB data.
So I decided to use ext2 formated HDD.
But write time on ext2 is much larger than FAT32.
HOW CAN I IMPROVE WRITING THROUGHPUT OF EXT2 FS

Niraj

camorri · 07-01-2009, 09:49 AM

Write time to a drive depends on a lot of factors, not just the file system type. Ext2 is not slow by its nature.

You did not state the type of drive, sata, ide etc. Is it internal or an external drive? If it is external, what type of connection do you have?

It is possible to 'tune' HDD performance on some drive types. There is a utility called hdparm. Be cautious, do some reading before you use it. It can be dangerous, and can cause loss of data. There are tutorials on the web on how to use it. I have used it on IDE drives, but be careful. Back up all data before you decide to use it. If you do the wrong thing, you can loose all your data.

Niraj Kulkarni · 07-01-2009, 10:19 AM

Hi ,
thanks for quick reply. here are the datails you require

* ped drive : external , normal data traveller. 2GB.
* No other transaction on USB bus.
* Time for 1MB data in chuncks of 64KB
FAT32 = 1.9 sec.
EXT2 = 6.6 sec.
Above observations shows ext2 write many other things along with actual data.
Niraj

Niraj Kulkarni · 07-02-2009, 07:47 AM

Hi,
I also understand that
* in ext2 fs the complete space is divided in "n Groups".
* each Group has : super block , group descriptor,blk bitmap etc.
* Now the fs must update these super block + group decriptor after every Group (4096 KB max)is filled up .
Is this the reason for delay.

In case of FAT32
I can see only one write after actual data write.

All logs seen on CATC.

Can I some how tell the file system to update superblock etc at the end.
"noatime" during mount did not serve the purpose.
Please help.....
Niraj

chrism01 · 07-03-2009, 02:46 AM

Exactly which distro and version on Linux have you got?
'Linux 2.4' doesn't really tell us anything.
If that's the kernel version

uname -a

then that's really old. All the current ones have 2.6.x

Niraj Kulkarni · 07-03-2009, 04:36 AM

Hi,
I am using Linux 2.4.18.
I also understand the "Block size" with which i format my pen drive in ext2 also matters.By default it is 4096 Bytes.And some thing related to
"block bit map" and "Inode bit map" come into picture.

I need to write 1MB data in less than or equal to 2 sec.

Niraj Kulkarni · 07-06-2009, 03:40 AM

Hi,
I have got a general idea about how ext2 fs works. Like there is the Superblock , Inode structure , Group descriptor etc.

In the Inode structure : Direct blocks , Indirect blocks , double indirect blocks.

I figured out how after "12" direct blocks are used up how the Indrect block comes into the picture.

Can any one tell me that : I can see the Superblock is read once while mounting the pen drive. wether the Superblock is modifed or not. If so at what time it is modified.
Niraj