New to reiserfs

New to reiserfs

[JPASTORM]

Hi,

I'm new to this surprising file system. Currently I have a Linux Red Hat
6.2 server for testing, with two partitions (/ and /boot). I'm running the
2.2.14-5.0 kernel and I have several questions about reiserfs:

1.- Do I necessarily have to update to the 2.2.20 kernel so as to use
2.2.20-reiserfs patch?
2.- Can I migrate from ext2 to reiserfs without loosing data (I know I
should always backup my data) or should I have to format my new reiserfs
partitions?
3.- Is there any partition in other servers (in production) where it is
advisable to stay with the ext2 filesystem?
4.- I have a PIII 1 GHz, 512 MB RAM, SCSI server where I run sendmail, bind
and squid. Will I have problems with performance if I migrate to reiserfs?
What's the counterpart of dealing with a journaling filesystem?

Thanks in advance.

Juan Pastor
E-mail: jpastorm@esade.edu

Centro de Proceso de Datos
Fundación ESADE
Av. Pedralbes, 60-62
08034 Barcelona

Tel  +34 932806162 ext. 2562
Fax  +34 932048105

Re: New to reiserfs

[Oleg Drokin]

Hello!

On Mon, May 13, 2002 at 11:34:29AM +0200, JPASTORM@esade.edu wrote:

> I'm new to this surprising file system. Currently I have a Linux Red Hat
> 6.2 server for testing, with two partitions (/ and /boot). I'm running the
> 2.2.14-5.0 kernel and I have several questions about reiserfs:

> 1.- Do I necessarily have to update to the 2.2.20 kernel so as to use
> 2.2.20-reiserfs patch?

No, but it is not guaranteed that that patch would apply to older kernels.
Also 2.2.14 kernel is a very old one, and it is willed with bugs and security
holes (e.g. anyone with local account may obtain root access in seconds).
So it is good idea to upgrade the kernel regardless of whenever you plan to
use reiserfs or not.

> 2.- Can I migrate from ext2 to reiserfs without loosing data (I know I
> should always backup my data) or should I have to format my new reiserfs
> partitions?

No. Currently you need to do full backup/mkfs/restore cycle.

> 3.- Is there any partition in other servers (in production) where it is
> advisable to stay with the ext2 filesystem?

I usually have very small "rescue" ext2 partition with all the necessary tools
present to ercover from various system disasters, I also never mount that
partition, except when I need to update some tools there.
ext2 was choosen as an fstype because 99% of all kernels are built with
ext2 support built-in, I guess.
In such a scenario, if I loose almost everything including rootfs,
I still can get any kernel and boot into my rescue partition to try and recover
stuff.

> 4.- I have a PIII 1 GHz, 512 MB RAM, SCSI server where I run sendmail, bind
> and squid. Will I have problems with performance if I migrate to reiserfs?

Not likely.

> What's the counterpart of dealing with a journaling filesystem?

Some of the diskspace is occupied for the journal (32M to be exact).
Also reiserfs is a balanced tree filesystem, and it puts somewhat higher
load on the CPU. (more likely to overheat if you do not have correct
cooling and stuff).
Also you usually do not see those fsck runs at startup after power failures.

Bye,
    Oleg

Re: New to reiserfs

[Hans Reiser]

Oleg Drokin wrote:

>Hello!
>
>On Mon, May 13, 2002 at 11:34:29AM +0200, JPASTORM@esade.edu wrote:
>
>  
>
>>I'm new to this surprising file system. Currently I have a Linux Red Hat
>>6.2 server for testing, with two partitions (/ and /boot). I'm running the
>>2.2.14-5.0 kernel and I have several questions about reiserfs:
>>    
>>
>
>  
>
>>1.- Do I necessarily have to update to the 2.2.20 kernel so as to use
>>2.2.20-reiserfs patch?
>>    
>>
>
>No, but it is not guaranteed that that patch would apply to older kernels.
>Also 2.2.14 kernel is a very old one, and it is willed with bugs and security
>holes (e.g. anyone with local account may obtain root access in seconds).
>So it is good idea to upgrade the kernel regardless of whenever you plan to
>use reiserfs or not.
>
>  
>
>>2.- Can I migrate from ext2 to reiserfs without loosing data (I know I
>>should always backup my data) or should I have to format my new reiserfs
>>partitions?
>>    
>>
>
>No. Currently you need to do full backup/mkfs/restore cycle.
>
>  
>
>>3.- Is there any partition in other servers (in production) where it is
>>advisable to stay with the ext2 filesystem?
>>    
>>
>
>I usually have very small "rescue" ext2 partition with all the necessary tools
>present to ercover from various system disasters, I also never mount that
>partition, except when I need to update some tools there.
>ext2 was choosen as an fstype because 99% of all kernels are built with
>ext2 support built-in, I guess.
>In such a scenario, if I loose almost everything including rootfs,
>I still can get any kernel and boot into my rescue partition to try and recover
>stuff.
>
>  
>
>>4.- I have a PIII 1 GHz, 512 MB RAM, SCSI server where I run sendmail, bind
>>and squid. Will I have problems with performance if I migrate to reiserfs?
>>
sendmail will be lower in performance when using reiserfs unless you use 
the latest not yet released patches and turned data journaling on.  Do 
you really push the performance limits of the machine as a mail server?

squid will benefit from your putting all files in one directory.

>>    
>>
>
>Not likely.
>
>  
>
>>What's the counterpart of dealing with a journaling filesystem?
>>    
>>
>
>Some of the diskspace is occupied for the journal (32M to be exact).
>Also reiserfs is a balanced tree filesystem, and it puts somewhat higher
>load on the CPU. (more likely to overheat if you do not have correct
>cooling and stuff).
>Also you usually do not see those fsck runs at startup after power failures.
>
>Bye,
>    Oleg
>
>
>  
>

Re: New to reiserfs

[Dieter Nützel]

On Monday 13 May 2002 10:07, Hans Reiser wrote:
> >>4.- I have a PIII 1 GHz, 512 MB RAM, SCSI server where I run sendmail,
> >>bind and squid. Will I have problems with performance if I migrate to
> >>reiserfs?
> >>
> sendmail will be lower in performance when using reiserfs unless you use 
> the latest not yet released patches and turned data journaling on.

More speed numbers on this to come with related post.
> Do you really push the performance limits of the machine as a mail server?

You mean if it is worth?

> squid will benefit from your putting all files in one directory.

So I should clobber my squid partition/dir and reconfigure to put all files 
into only one directory and let the squid hierarchy alone?

Thanks,
	Dieter

-- 
Dieter Nützel
Graduate Student, Computer Science

University of Hamburg
Department of Computer Science
@home: Dieter.Nuetzel@hamburg.de

Re: Re: New to reiserfs

[Joe Cooper]

Dieter Nützel wrote:
> On Monday 13 May 2002 10:07, Hans Reiser wrote:

>>squid will benefit from your putting all files in one directory.

Hi Hans and all,

Out of curiosity...When did this become true?  I haven't tested in some 
time, but way back in 2.4.0pre days it was very far from reality 
(all-in-one-dir was about 20-30% slower than the standard default of 
x/256/256).

I'll be happy to run some Polygraph runs of this...I wasn't aware 
anything had changed, however.  Perhaps someone has a pointer for the 
relevant changelog entries?
-- 
Joe Cooper <joe@swelltech.com>
http://www.swelltech.com
Web Caching Appliances and Support

Re: New to reiserfs

[Hans Reiser]

Dieter Nützel wrote:

>On Monday 13 May 2002 10:07, Hans Reiser wrote:
>  
>
>>>>4.- I have a PIII 1 GHz, 512 MB RAM, SCSI server where I run sendmail,
>>>>bind and squid. Will I have problems with performance if I migrate to
>>>>reiserfs?
>>>>
>>>>        
>>>>
>>sendmail will be lower in performance when using reiserfs unless you use 
>>the latest not yet released patches and turned data journaling on.
>>    
>>
>
>More speed numbers on this to come with related post.
>  
>
>>Do you really push the performance limits of the machine as a mail server?
>>    
>>
>
>You mean if it is worth?
>
>  
>
>>squid will benefit from your putting all files in one directory.
>>    
>>
>
>So I should clobber my squid partition/dir and reconfigure to put all files 
>into only one directory and let the squid hierarchy alone?
>
>Thanks,
>	Dieter
>
>  
>
I don't understand you.  

You should put squid into one big directory (not using their kludge that 
avoids making directories too large by using a tree)  unless you have 
multiple processors (in which case the VFS directory giant lock will 
hurt you).

Hans

Re: Re: New to reiserfs

[Hans Reiser]

Joe Cooper wrote:

> Dieter Nützel wrote:
>
>> On Monday 13 May 2002 10:07, Hans Reiser wrote:
>
>
>>> squid will benefit from your putting all files in one directory.
>>
>
> Hi Hans and all,
>
> Out of curiosity...When did this become true?  I haven't tested in 
> some time, but way back in 2.4.0pre days it was very far from reality 
> (all-in-one-dir was about 20-30% slower than the standard default of 
> x/256/256).
>
> I'll be happy to run some Polygraph runs of this...I wasn't aware 
> anything had changed, however.  Perhaps someone has a pointer for the 
> relevant changelog entries?

Perhaps I misremember, Nikita, please comment.

Hans

Re: New to reiserfs

[Dieter Nützel]

On Monday 13 May 2002 22:57, Hans Reiser wrote:
> Dieter Nützel wrote:
> >On Monday 13 May 2002 10:07, Hans Reiser wrote:
> >>>>4.- I have a PIII 1 GHz, 512 MB RAM, SCSI server where I run sendmail,
> >>>>bind and squid. Will I have problems with performance if I migrate to
> >>>>reiserfs?
> >>
> >>sendmail will be lower in performance when using reiserfs unless you use
> >>the latest not yet released patches and turned data journaling on.
> >
> >More speed numbers on this to come with related post.
> >
> >>Do you really push the performance limits of the machine as a mail
> >> server?
> >
> >You mean if it is worth?

Here I don't understand you that's why I asking.

> >>squid will benefit from your putting all files in one directory.
> >
> >So I should clobber my squid partition/dir and reconfigure to put all
> > files into only one directory and let the squid hierarchy alone?
> >
> >Thanks,
> >	Dieter
>
> I don't understand you.
>
> You should put squid into one big directory (not using their kludge that
> avoids making directories too large by using a tree)

So you understand me right...;-)

> unless you have multiple processors (in which case the VFS directory giant
> lock will hurt you).

BKL?

Where is the limit 2, 4, or even more CPUs?
I'll have two in some days.

Thanks,
	Dieter

PS You know that I'm on the preemption+lock-break, O(1)-scheduler track...;-)

Re: New to reiserfs

[Chris Mason]

On Mon, 2002-05-13 at 17:24, Dieter Nützel wrote:

> >
> > You should put squid into one big directory (not using their kludge that
> > avoids making directories too large by using a tree)
> 
> So you understand me right...;-)
> 
> > unless you have multiple processors (in which case the VFS directory giant
> > lock will hurt you).
> 
> BKL?
> 
> Where is the limit 2, 4, or even more CPUs?
> I'll have two in some days.

You probably want one directory per squid process.  The VFS layer does
semaphore locking to prevent races between people reading the directory
and people changing the directory.  If you've just got one big
directory, all the squid processes will end up waiting on each other.

More directories mean more time wasted changing the directory stat data,
and ram wasted on reading the stat data.  You see this more with
hundreds or thousands of directories.

-chris