Hello! I'm using a CompactFlash as storage device. Since those CF cards only have limited write cycles (CF does wear-levelling by itself, but you don't want to write too many timet so the card) i was wondering by what a factor the journaling of ext3 increases the write accesses to the CompactFlash compared to ext2. Thanks a lot already for your help! Sincerely Chris Braun
Andreas Dilger <adilger@clusterfs.com> wrote 11.02.2004 18:23>On Feb 11, 2004 15:55 +0100, christian.braun@ch.abb.com wrote: >> I'm using a CompactFlash as storage device. Since those CF cards onlyhave>> limited write cycles (CF does wear-levelling by itself, but you don'twant>> to write too many timet so the card) i was wondering by what a factorthe>> journaling of ext3 increases the write accesses to the CompactFlash >> compared to ext2. Thanks a lot already for your help! > >You will probably wear out the journal area quickly, unless your device >has internal wear leveling (it might). Instead of ext3 you should use >a filesystem designed for such devices - JFFS2 or similar.Well, the CompactFlash card I use does internal wear-leveling, so all that should count I think are the write cycles. So in that case ext2/3 would not be to big of a disadvantage, would it? But the 2-or-3 question arises since I like the stability of ext3, but don't really know the cost in respect to wearing out the card because of additional write cycles. Thanks a lot! Chris Braun
On Wed, 2004-02-11 at 09:55, christian.braun@ch.abb.com wrote:> Hello! > > I'm using a CompactFlash as storage device. Since those CF cards only > have limited write cycles (CF does wear-levelling by itself, but you > don't want to write too many timet so the card) i was wondering by > what a factor the journaling of ext3 increases the write accesses to > the CompactFlash compared to ext2. Thanks a lot already for your help!Is there any reason you're looking at ext2/3 rather than using jffs2, which is specifically designed for flash? http://sources.redhat.com/jffs2/ -- Matthew Berg <galt@gothpoodle.com>
Hi, On Wed, 2004-02-11 at 14:55, christian.braun@ch.abb.com wrote:> I'm using a CompactFlash as storage device. Since those CF cards only > have limited write cycles (CF does wear-levelling by itself, but you > don't want to write too many timet so the card) i was wondering by > what a factor the journaling of ext3 increases the write accesses to > the CompactFlash compared to ext2. Thanks a lot already for your help!It increases the number of writes a bit, but in many cases might actually reduce the number of overwrites for certain blocks like the superblock, which can be an advantage for those CF cards that don't do wear-levelling. But it's really not a filesystem designed for flash. --Stephen
Hello!
Message from "Stephen C. Tweedie" <sct at redhat.com> received
on 13.02.2004
12:12
13.02.2004 12:12
"Stephen C. Tweedie" <sct at redhat.com>
To: christian.braun at ch.abb.com
cc: ext3 users list <ext3-users at redhat.com>
Subject: Re: ext3 Overhead
Hi,
On Wed, 2004-02-11 at 14:55, christian.braun at ch.abb.com wrote:
> I'm using a CompactFlash as storage device. Since those CF cards only
> have limited write cycles (CF does wear-levelling by itself, but you
> don't want to write too many timet so the card) i was wondering by
> what a factor the journaling of ext3 increases the write accesses to
> the CompactFlash compared to ext2. Thanks a lot already for your help!
It increases the number of writes a bit, but in many cases might
actually reduce the number of overwrites for certain blocks like the
superblock, which can be an advantage for those CF cards that don't do
wear-levelling. But it's really not a filesystem designed for flash.
--Stephen
On Wed, 2004-02-11 at 14:55, christian.braun at ch.abb.com wrote:
>> I'm using a CompactFlash as storage device. Since those CF cards
only
>> have limited write cycles (CF does wear-levelling by itself, but you
>> don't want to write too many timet so the card) i was wondering by
>> what a factor the journaling of ext3 increases the write accesses to
>> the CompactFlash compared to ext2. Thanks a lot already for your help!
>
>It increases the number of writes a bit, but in many cases might
>actually reduce the number of overwrites for certain blocks like the
>superblock, which can be an advantage for those CF cards that don't do
>wear-levelling. But it's really not a filesystem designed for flash.
Well, as I said my CF card does wear-levelling, so that's not to worry
about. Still, as you said, there is a difference in the number of write
accesses between ext2 and ext3... I just need to know in what region that
difference is... is it 3 times... or 30 times... or 300... or even more?
Thank you!
Christian Braun