[gentoo-user] ext3: 10% non-contiguous

[gentoo-user] ext3: 10% non-contiguous

[Rafael Fernández López]

Hi,

	Each 20 times that my hard disk is mounted, my ext3 partition (is the
only one that I have) gets checked for inconsistencies.

	On the last times that that task has been runned, it tells me that ~
(more or less) the 10% of the filesystem is non-contiguous. I suppose
that the problem is that I've saved and then deleted some files really
big, and there's a hole.

	Well, I'd like to recover those holes (that 10% of the disk) and how to
do it, because I've tried with e2fsck with different options and read
"man e2fsck" with no possitive results.

Thanks,
Rafael Fernández López.

-- 
"A la vista de suficientes ojos todos los errores resultan evidentes" -
Linus Torvalds

-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] ext3: 10% non-contiguous

[Benno Schulenberg]

Rafael Fernández López wrote:
> ~ (more or less) the 10% of the filesystem is
> non-contiguous. I suppose that the problem is that I've saved and
> then deleted some files really big, and there's a hole.
>
> 	Well, I'd like to recover those holes (that 10% of the disk)

There are no holes, there is nothing to recover.  It just means that 
10% of the files are not allocated as a single contiguous string of 
blocks, which makes reading these files just a little bit slower.  
Nothing to worry about.

If you really want to "defrag" the file system, then copy everything 
to another partition, recreate the file system, and copy everything 
back:  cd /parti1; tar -cf - . | (cd /parti2; tar -xpvf -)
But this isn't worth the time it costs.

Benno
-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] ext3: 10% non-contiguous

[Dale]

Rafael Fernández López wrote:

>Hi,
>
>Well, I'd like to recover those holes (that 10% of the disk) and how to
>do it, because I've tried with e2fsck with different options and read
>"man e2fsck" with no possitive results.
>
>Thanks,
>Rafael Fernández López.
>
>  
>
There was a guru on the forums that explained to me that it does not
mean the files are fragmented or lost.  If you want, I'll try to find
the thread and post a link.  It made a lot of sense after I read it. 
Basically, you haven't lost anything so there is nothing to gain. 

I can't remember for sure but I think it was on the LQ forums.  I think
I can find it but it may take a bit of looking.  It was a while ago.

Later

:D :D :D
-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] ext3: 10% non-contiguous

[Joshua Schmidlkofer]

[-- Attachment #1: Type: text/plain, Size: 1142 bytes --]

On 10/31/05, Dale <dalek@exceedtech.net> wrote:
>
> Rafael Fernández López wrote:
>
> >Hi,
> >
> >Well, I'd like to recover those holes (that 10% of the disk) and how to
> >do it, because I've tried with e2fsck with different options and read
> >"man e2fsck" with no possitive results.
> >
> >Thanks,
> >Rafael Fernández López.
> >
> >
> >
> There was a guru on the forums that explained to me that it does not
> mean the files are fragmented or lost. If you want, I'll try to find
> the thread and post a link. It made a lot of sense after I read it.
> Basically, you haven't lost anything so there is nothing to gain.
>
> I can't remember for sure but I think it was on the LQ forums. I think
> I can find it but it may take a bit of looking. It was a while ago.



For a more sustainable situation, switch to XFS [It involved a
backup/format/restore by whatever means you want] In any case, xfs has a
tool called 'xfs_fsr' Which means 'file system reorganizer'. It does
defragmentation, and balances some other stuff too. I run it weekly on my
production servers, and nightly on mostof my workstations.

js

[-- Attachment #2: Type: text/html, Size: 1580 bytes --]

[OT?] Re: [gentoo-user] ext3: 10% non-contiguous

[Peter Gordon]

[-- Attachment #1: Type: text/plain, Size: 896 bytes --]

On Mon, 2005-10-31 at 20:34 -0800, Joshua Schmidlkofer wrote:
> For a more sustainable situation, switch to XFS [It involved a
> backup/format/restore by whatever means you want]  In any case, xfs
> has a tool called 'xfs_fsr'  Which means 'file system reorganizer'.
> It does defragmentation, and balances some other stuff too.   I run it
> weekly on my production servers, and nightly on most of my
> workstations.

Thus why it is broken by design in my view. A good filesystem should not
need to be defragmented. All filesystems will become fragmented over
time, but a filesystem which is well-behaved should take minimal, if
any, performance loss from it. 

For what it's worth, I've never had a *single* problem with Ext3, and
I've been using it with various distributions since I first started
playing with GNU/Linux a few weeks after Fedora Core 1 was released.

--Peter

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

Re: [OT?] Re: [gentoo-user] ext3: 10% non-contiguous

[Dale]

Peter Gordon wrote:

>
>For what it's worth, I've never had a *single* problem with Ext3, and
>I've been using it with various distributions since I first started
>playing with GNU/Linux a few weeks after Fedora Core 1 was released.
>
>--Peter
>  
>
I use reiserfs and have had no problems either.  I still remember how
bad windoze used to be though.  We would run defrag programs all night
they were so bad.  Even my brother's Win XP with NTFS gets really bad
after a while.  All he does is play games and check email.

I'm going to go see if I can find that thread in the forums. 

I'll be back.  LOL

Dale

-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] ext3: 10% non-contiguous

[Harald Arnesen]

Joshua Schmidlkofer <joshland@gmail.com> writes:

> For a more sustainable situation, switch to XFS [It involved a
> backup/format/restore by whatever means you want]

And if you do, make sure you have a good UPS.
-- 
Hilsen Harald.

-- 
gentoo-user@gentoo.org mailing list

Re: [OT?] Re: [gentoo-user] ext3: 10% non-contiguous

[Richard Fish]

Peter Gordon wrote:

>On Mon, 2005-10-31 at 20:34 -0800, Joshua Schmidlkofer wrote:
>  
>
>>For a more sustainable situation, switch to XFS [It involved a
>>backup/format/restore by whatever means you want]  In any case, xfs
>>has a tool called 'xfs_fsr'  Which means 'file system reorganizer'.
>>It does defragmentation, and balances some other stuff too.   I run it
>>weekly on my production servers, and nightly on most of my
>>workstations.
>>    
>>
>
>Thus why it is broken by design in my view. A good filesystem should not
>need to be defragmented. All filesystems will become fragmented over
>time, but a filesystem which is well-behaved should take minimal, if
>any, performance loss from it. 
>  
>

The performance impact of fragmentation is unavoidable.  It is a simple 
physical fact that seeking the heads on a disk drive and waiting for the 
platter to spin around to a fragment is a time-consuming operation, 
taking between 6ms (on very fast SCSI hard drives) and 20ms (on very 
slow laptop hard drives).  The average 7200rpm desktop drive has an 
access time of around 12ms.  At that speed, anything smaller than about 
one megabyte can actually take longer to access than it takes to read.  
The only way to avoid the performance impact of fragmentation is to not 
fragment to begin with, which is what most linux filesystems try to do, 
and where Microsoft fails miserably.

The way xfs defends against fragmentation is a bit smarter than ext2/3 
at this point, because it delays the allocation step until the data is 
actually written to disk.  This means that it can wait until the last 
possible moment before deciding where on the disk the file (or fragment 
of a file) should live, and thus should create fewer fragments overall.  
This is assuming that whatever is creating or appending to the file 
doesn't flush after every write of course...

Ext2/3 tackles fragmentation by pre-allocating blocks when a file is 
growing.  It is effective, but would be even more effective with delayed 
allocation.  Note that this pre-allocation is not preserved when the 
file is closed, it is only active for files that are open and growing.

Based on what the developers presented at the 2005 OLS, delayed 
allocation, and an extents-based format (ext4?) are coming:

http://www.linuxsymposium.org/2005/linuxsymposium_procv1.pdf

-Richard

-- 
gentoo-user@gentoo.org mailing list

Re: [OT?] Re: [gentoo-user] ext3: 10% non-contiguous

[Peter Gordon]

Richard Fish said:
> Based on what the developers presented at the 2005 OLS, delayed
> allocation, and an extents-based format (ext4?) are coming:
>
> http://www.linuxsymposium.org/2005/linuxsymposium_procv1.pdf
That looks very intriguing. :-D

Thanks for your thorough explanations, Richard!

--Peter
-- 
gentoo-user@gentoo.org mailing list