Arch Linux

StaticPhilly

Member

From: UK

Registered: 2009-05-15

Posts: 53

[Answered] EXT2 or EXT4 for USB Drive

hello,

OK i managed to work out the installation process, finerly and all is looking good. How ever i am installing onto a USB drive so for my final install i would like to know what format to put my partition in.

I have a USB 640GB Drive of which about 100GB is going to be used for ArchLinux. Now i read in the wiki (here) that its best to format in EXT2 with USB media because of flash.
Now, I dont know if this applys to my HDD, but it is possible that its using a flash style bourd for the USB connection even tho its accually a standard drive inside its casing.

So, i am unsure if that statment in the wiki still applys now we have EXT4, can anyone tell me if this is so?

thanks.

Last edited by StaticPhilly (2009-05-15 19:34:55)

---

Lightweight software dose not mean less! It just means you have to get your finger out and make it do and look like you want!

dmartins

Member

Registered: 2006-09-23

Posts: 360

Re: [Answered] EXT2 or EXT4 for USB Drive

Your external hard drive wouldn't be flash based. Flash memory would refer to the small USB thumb drives and possibly CF cards, SD cards, etc. As I understand it, flash memory gets worn out more quickly when using ext3 or ext4 because the journal is written to the same location over and over again. For a regular hard drive such as yours, repeated writes are not a problem so should be safe to use ext3/4.

StaticPhilly

Member

From: UK

Registered: 2009-05-15

Posts: 53

Re: [Answered] EXT2 or EXT4 for USB Drive

thanks martins, that cleared things up for me.

EXT4 it is then, just thought id check before started using it on a daily basis.

thanks again

---

Lightweight software dose not mean less! It just means you have to get your finger out and make it do and look like you want!

bender02

Member

From: UK

Registered: 2007-02-04

Posts: 1,328

Re: [Answered] EXT2 or EXT4 for USB Drive

As I understand it, flash memory gets worn out more quickly when using ext3 or ext4 because the journal is written to the same location over and over again.

This is not quite true. From the point of the view of the kernel, it might look like it's written to the same place, but the controllers and cards these days are (or try to be) pretty smart, so they do what's called "wear levelling" on the hardware level, so that the data gets physically written in such a way that most of the places on the card are written to about the same number of times.
The thing with the journaling is that you get more writes than without journaling. [Considering the lifetime of today's flash based devices, it's becoming more of an urban legend.]

dmartins

Member

Registered: 2006-09-23

Posts: 360

Re: [Answered] EXT2 or EXT4 for USB Drive

As I understand it, flash memory gets worn out more quickly when using ext3 or ext4 because the journal is written to the same location over and over again.

This is not quite true. From the point of the view of the kernel, it might look like it's written to the same place, but the controllers and cards these days are (or try to be) pretty smart, so they do what's called "wear levelling" on the hardware level, so that the data gets physically written in such a way that most of the places on the card are written to about the same number of times.
The thing with the journaling is that you get more writes than without journaling. [Considering the lifetime of today's flash based devices, it's becoming more of an urban legend.]

Excellent! Thanks for the clarification!

brendan

Member

From: UK

Registered: 2009-05-16

Posts: 130

Website

Re: [Answered] EXT2 or EXT4 for USB Drive

On a small usb stick a journaled filesystem is simply a waste of space, for an external harddrive it is alot better.

Wear levelling is not at the filesystem level. And unfortunately you can't use JFFS2 on usb sticks