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fasza2 is offline fasza2
2011-04-10 , 00:15
Posts: 187 | Thanked: 96 times | Joined on Sep 2010 @ London, UK
#11
When the fat file systems were created the developers didn't think that files larger then 4 GB will be used in the near future. FAT32 was created 15 years ago...
 

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evan is offline evan
2011-04-10 , 04:14
Posts: 136 | Thanked: 115 times | Joined on Jul 2010 @ Greece
#12
the wiki guides you to convert the 2gb /home and not the big fat partition. I prefrer it that way,although tempted to resize the thing.
I think now it boots faster and operations like installing apps with appman is faster.
I tried some time with dd commands to test speed of wriiting files but it does not seem consistent, so there.
 
9000 is offline 9000
2011-04-10 , 04:38
Posts: 1,425 | Thanked: 983 times | Joined on May 2010 @ Hong Kong
#13
ext4 is faster than ext2 and ext3 for transferring large amount of small files, while vfat is good for transferring small amount of large files. Therefore, if the purpose of your external flash is to store media files, you may not need to reformat.

In addition, without wear levelling, ext4 is not the best choice for flash media. I'm not sure if the latest development has included wear levelling in ext4, you may search 'wear levelling' in t.m.o for detail discussion.
 
iDont is offline iDont
2011-04-10 , 13:58
Posts: 268 | Thanked: 1,053 times | Joined on May 2010 @ The Netherlands
#14
Originally Posted by evan View Post
thanks, very much for the wiki. I managed to convert /home to ext4 with your instructions.
So now I am dependent on power kernel I guess.
I'm glad to hear that
And yes, you must keep using a kernel that supports the chosen filesystem (like kernel-power).

Originally Posted by 9000 View Post
ext4 is faster than ext2 and ext3 for transferring large amount of small files, while vfat is good for transferring small amount of large files. Therefore, if the purpose of your external flash is to store media files, you may not need to reformat.

In addition, without wear levelling, ext4 is not the best choice for flash media. I'm not sure if the latest development has included wear levelling in ext4, you may search 'wear levelling' in t.m.o for detail discussion.
I don't completely agree with your post.

First things first: as said in the post above yours, the wiki is about reformatting the /home partition, not the big vfat one. Maybe this should be made more clear in the wiki page. The "need" to reformat might be an overstatement, it's more like "want" to reformat. Don't forget that the majority of users don't want to repartition/change FS at all.

Anyway, judging by my (simple) benchmarks, ext4 is quicker in copying big files too. A more extensive benchmark is to be found here.

As far as I know wear-leveling, at least on the N900 its NAND flash, is not managed by the filesystem so this should be a non-issue.
 

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9000 is offline 9000
2011-04-10 , 14:38
Posts: 1,425 | Thanked: 983 times | Joined on May 2010 @ Hong Kong
#15
Originally Posted by iDont View Post
I don't completely agree with your post.


Originally Posted by iDont View Post
First things first: as said in the post above yours, the wiki is about reformatting the /home partition, not the big vfat one. Maybe this should be made more clear in the wiki page. The "need" to reformat might be an overstatement, it's more like "want" to reformat. Don't forget that the majority of users don't want to repartition/change FS at all.
I am not commenting the wiki, nor whether there's a need to reformat all partition in N900. It's okay if one wants to format any partition with any fs, as long as they're willingly to take the risk.

I'm just commenting on the suitability of using ext4 fs on flash media. May be I should have stated it explicitly next time before posting.

Originally Posted by iDont View Post
Anyway, judging by my (simple) benchmarks, ext4 is quicker in copying big files too. A more extensive benchmark is to be found here.
Thank you for sharing the links. However, I found that neither of them include vfat in the benchmark, rather I found one here.

Nevertheless, I'm not going to defend for vfat. I've no sentimental attachment toward vfat, I'm glad to know ext4 is better than vfat.

For the performance, we can always do our own benchmark to convince ourself. There's no need to argue on that. Take it easy. ^^

Originally Posted by iDont View Post
As far as I know wear-leveling, at least on the N900 its NAND flash, is not managed by the filesystem so this should be a non-issue.
Again I'm not talking about reformatting NAND, I'm just talking about ext4 on flash media. BTW, NAND in N900 is formatted in UBIFS, which does not work on top block device, but still it's a file-system anyway.

UBI itself is a wear-leveling subsystem but I'm not referring to that in my point. Without wear-leveling, ext4 is not the best choice for flash media. Ext4 does not handle wear-leveling in its original design, but flash manufacturers consider including wear-leveling in hardware so the problem would be solved in the future.

Just for your information.
 
iDont is offline iDont
2011-04-10 , 17:38
Posts: 268 | Thanked: 1,053 times | Joined on May 2010 @ The Netherlands
#16
Thank you for your elaborate post

Originally Posted by 9000 View Post
I am not commenting the wiki, nor whether there's a need to reformat all partition in N900. It's okay if one wants to format any partition with any fs, as long as they're willingly to take the risk.

I'm just commenting on the suitability of using ext4 fs on flash media. May be I should have stated it explicitly next time before posting.
Ah, that explains a bit. Considering the topic, I assumed you were talking about the N900.

Originally Posted by 9000 View Post
Thank you for sharing the links. However, I found that neither of them include vfat in the benchmark, rather I found one here.

Nevertheless, I'm not going to defend for vfat. I've no sentimental attachment toward vfat, I'm glad to know ext4 is better than vfat.

For the performance, we can always do our own benchmark to convince ourself. There's no need to argue on that. Take it easy. ^^
Same goes here. As you can't use vfat as /home, I saw no value in including it in the benchmark. We weren't talking about the same thing

I'm with you about everyone convincing their selves. In fact, I performed the benchmark to decide for myself which FS to choose (or more precise: which Reiser4 mkfs options were the best), but I thought I could post a summary anyway as it might be of use to other people. No need to start a religious (filesystem) war indeed; I hoped to make that point by stating in the wiki that "there is no 'one size fits all' type of filesystem"

Originally Posted by 9000 View Post
Again I'm not talking about reformatting NAND, I'm just talking about ext4 on flash media. BTW, NAND in N900 is formatted in UBIFS, which does not work on top block device, but still it's a file-system anyway.

UBI itself is a wear-leveling subsystem but I'm not referring to that in my point. Without wear-leveling, ext4 is not the best choice for flash media. Ext4 does not handle wear-leveling in its original design, but flash manufacturers consider including wear-leveling in hardware so the problem would be solved in the future.

Just for your information.
I mixed up some terms by stating NAND everywhere in my posts instead of eMMC. Of course ext4, or any 'regular' FS for that matter, can't be used on a raw flash device like the NAND. I've just corrected the name of the wiki page.
Last edited by iDont; 2011-04-10 at 17:58. Reason: Updated post with wiki name change
 

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9000 is offline 9000
2011-04-11 , 01:30
Posts: 1,425 | Thanked: 983 times | Joined on May 2010 @ Hong Kong
#17
Originally Posted by iDont View Post
I'm with you about everyone convincing their selves. In fact, I performed the benchmark to decide for myself which FS to choose (or more precise: which Reiser4 mkfs options were the best), but I thought I could post a summary anyway as it might be of use to other people. No need to start a religious (filesystem) war indeed; I hoped to make that point by stating in the wiki that "there is no 'one size fits all' type of filesystem"
Yep reiser4 is the fastest fs around. It's a .....real killer

Since you're interested in that subject. FYI. I performed some tests on all the fs years ago for a major enterprise deployment. It's concluded that JFS scored the best on almost all categories, especially fault tolerant. Say you can cold boot the system multiple times during journal recovery without losing any data. Only jfs and ext3 can survive this test (survival of ext3 is obvious, as it's just ext2+plain text journal )
Last edited by 9000; 2011-04-11 at 01:33.
 

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Tigerite is offline Tigerite
2011-05-20 , 11:04
Posts: 284 | Thanked: 320 times | Joined on May 2010 @ Peterborough, UK
#18
Originally Posted by retsaw View Post
Early versions of ext4 had issues, after a bit of googling I found this, is this issue fixed in the version of ext4 included with kernel power?

There is also the consideration that ext4 isn't included in the stock kernel, which might cause a problem if you need/want to switch back.
From what I can tell, no. However, I generated a diff (which can be found here) between the 2.6.28.10 snapshot and latest on http://git.kernel.org/?p=linux/kerne...-stable-2.6.28 and fixed the few discrepancies, so that it now patches against kernel-power47 (and BFS ). Some had already been applied, some had been partially applied and one had had "force_da_alloc=1" added whereas the diff had an if statement added as well (so I went with the latter).

Please note that the patch has been updated since my original post - I'd erroneously included part of the ioctl.c diff that had already been applied, and although it would patch successfully it wouldn't compile (due to a duplicate case statement).

PS: I tried Reiser4, even added an edit into the wiki, but I had to backtrack as it was hammering my CPU and also I had the dmesg errors even with cluster=32K. Basically, my N900 just didn't like it one bit, which is a real shame I'd love to try out btrfs, but I can't find a backport to 2.6.28 anywhere (and it's only really been stable since 2.6.32 anyway) so it's probably not worth the trouble.
Last edited by Tigerite; 2011-05-20 at 11:45.
 
evan is offline evan
2011-05-20 , 12:55
Posts: 136 | Thanked: 115 times | Joined on Jul 2010 @ Greece
#19
I should say that I am running /home on ext4 for over a month now and I have not had any incident with filesystem corruption.
 
vi_ is offline vi_
2011-05-20 , 13:00
Posts: 1,680 | Thanked: 3,685 times | Joined on Jan 2011
#20
Originally Posted by evan View Post
I should say that I am running /home on ext4 for over a month now and I have not had any incident with filesystem corruption.
Do you 'feel' any improvment in emmc access?
__________________
N900: One of God's own prototypes. A high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die.
 

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