Perhaps this has been answered before...

Perhaps this has been answered before...

[Chris Zimmerman]

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I am new to the list, so forgive me if this is a FAQ: 

I have a Slack system running a patched 2.2.17 kernel with raidtools
0.90 that is running RAID 1 on 2 internal 20 GB IDE drives (one on each
bus).  Periodically, and now happening more frequently, the machine will
partially freeze.  I cannot login into the machine, but the IP address
still answers.  

Here is my fstab: 

/dev/md0       swap        swap        defaults   0   0 
/dev/md1       /        ext2        defaults   1   1 
/dev/md2       /var        ext2        defaults   1   1 
/dev/md3       /home        ext2        defaults   1   1 
none             /dev/pts  devpts     gid=5,mode=620  0   0 
none             /proc    proc        defaults   0   0 


Here is my raidtab: 

raiddev /dev/md0 
        raid-level              1 
        nr-raid-disks           2 
        nr-spare-disks          0 
        persistent-superblock   1 
        chunk-size              4 

        device                  /dev/hda1 
        raid-disk               0 
        device                  /dev/hdb1 
        raid-disk               1 
#       failed-disk             1 
# 
# 
raiddev /dev/md1 
        raid-level              1 
        nr-raid-disks           2 
        nr-spare-disks          0 
        persistent-superblock   1 
        chunk-size              4 

        device                  /dev/hda2 
        raid-disk             0 
        device                  /dev/hdb2 
        raid-disk               1 
# 
# 
raiddev /dev/md2 
        raid-level              1 
        nr-raid-disks           2 
        nr-spare-disks          0 
        persistent-superblock   1 
        chunk-size              4 

        device                  /dev/hda3 
        raid-disk             0 
        device                  /dev/hdb3 
        raid-disk               1 
# 
# 
raiddev /dev/md3 
        raid-level              1 
        nr-raid-disks           2 
        nr-spare-disks          0 
        persistent-superblock   1 
        chunk-size              4 

        device                  /dev/hda4 
        raid-disk             0 
        device                  /dev/hdb4 
        raid-disk               1 

I suspect that "maybe" my swap on md0 is causing the problem, but that
is a guess since I have nothing in the logs up to the time the machine
failed that indicates a problem.  Does anything jump out at you? 

Chris Zimmerman 




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Re: Perhaps this has been answered before...

[Mikael Johansson]

Hello Chris and All!

On 21 Aug 2002, Chris Zimmerman wrote:

> I have a Slack system running a patched 2.2.17 kernel with raidtools
> 0.90 that is running RAID 1 on 2 internal 20 GB IDE drives (one on each
> bus).  Periodically, and now happening more frequently, the machine will
> partially freeze.  I cannot login into the machine, but the IP address
> still answers.

> /dev/md0       swap        swap        defaults   0   0

> raiddev /dev/md0
>         raid-level              1

Having your swap space as RAID-1 is redundant indeed :-) You will be
better off changing it to RAID-0.

I however do not see why this should freeze your machine. Does "freeze"
here only mean that the console freezes? You say the IP address answers,
can you login from another machine? If it is the console you might want to
check for culprits elsewhere. We had similar problems on some new machines
here last year. If I remember correctly, it turned out to be some conflict
between PS/2-mice and X. Or maybe it was the graphics cards...

Have a nice day,
    Mikael J.
    http://www.helsinki.fi/~mpjohans/

Re: Perhaps this has been answered before...

[Mads Peter Bach]

Mikael Johansson wrote:

> 
> On 21 Aug 2002, Chris Zimmerman wrote:
> 
> 
>>/dev/md0       swap        swap        defaults   0   0
>>
> 
>>raiddev /dev/md0
>>        raid-level              1
>>
> 
> Having your swap space as RAID-1 is redundant indeed :-) You will be
> better off changing it to RAID-0.


Only if you don't care what happens when a disk crashes. With RAID-1, 
you'll be able to survive, with RAID-0 your system will crash, when it 
can't access the swap partition.

 
> I however do not see why this should freeze your machine.


Me neither. Swap on RAID-1 works fine for me (though on 2.4).

Regards,
Mads

Re: Perhaps this has been answered before...

[Chris Zimmerman]

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So where can I get the appropriate kernel patches for 2.4 and will I
have to update raidtools? 

Thanks, 
Chris Zimmerman 


On Wed, 2002-08-21 at 12:41, Mads Peter Bach wrote:
    Mikael Johansson wrote:
    
    > 
    > On 21 Aug 2002, Chris Zimmerman wrote:
    > 
    > 
    >>/dev/md0       swap        swap        defaults   0   0
    >>
    > 
    >>raiddev /dev/md0
    >>        raid-level              1
    >>
    > 
    > Having your swap space as RAID-1 is redundant indeed :-) You will be
    > better off changing it to RAID-0.
    
    
    Only if you don't care what happens when a disk crashes. With RAID-1, 
    you'll be able to survive, with RAID-0 your system will crash, when it 
    can't access the swap partition.
    
     
    > I however do not see why this should freeze your machine.
    
    
    Me neither. Swap on RAID-1 works fine for me (though on 2.4).
    
    Regards,
    Mads
    
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Re: Perhaps this has been answered before...

[Mads Peter Bach]

Chris Zimmerman wrote:

> So where can I get the appropriate kernel patches for 2.4 and will I
> have to update raidtools? 


No patches needed! Just install a bog-standard 2.4, and compile in 
support for raid.

You shouldn't need to update raidtools, but you may want to look at 
mdadm (http://www.cse.unsw.edu.au/~neilb/source/mdadm/) instead. It is 
superior to raidtools, IMHO.

Regards,
Mads

Re: Perhaps this has been answered before...

[Jakob Oestergaard]

On Wed, Aug 21, 2002 at 07:41:17PM +0200, Mads Peter Bach wrote:
...
> >I however do not see why this should freeze your machine.
> 
> 
> Me neither. Swap on RAID-1 works fine for me (though on 2.4).

RAID in 2.2 is seriously broken unless the RAID patches are applied.

With the patches, there are problems with stability in the case where
you actually swap on the RAID device.

With a recent 2.4 kernel, the swap stability problem should be gone. At
least swapping on RAID-1 works for me as well, on several systems here.

So just don't swap on RAID if you're on 2.2  :)   On 2.4 it should work.

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:.........................: putrid forms of man                :
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Re: Perhaps this has been answered before...

[Chris Zimmerman]

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Based on this, I have upgraded the system to 2.4.19.  Since this is a
cluster, I will run this kernel on the secondary (and it seems to be
working fine so far), then I will push this to the primary after about
30-60 days of stable operation.  Thanks to all for the suggestions and
help. 

Chris Zimmerman 

On Wed, 2002-08-21 at 18:53, Jakob Oestergaard wrote:
    On Wed, Aug 21, 2002 at 07:41:17PM +0200, Mads Peter Bach wrote:
    ...
    > >I however do not see why this should freeze your machine.
    > 
    > 
    > Me neither. Swap on RAID-1 works fine for me (though on 2.4).
    
    RAID in 2.2 is seriously broken unless the RAID patches are applied.
    
    With the patches, there are problems with stability in the case where
    you actually swap on the RAID device.
    
    With a recent 2.4 kernel, the swap stability problem should be gone. At
    least swapping on RAID-1 works for me as well, on several systems here.
    
    So just don't swap on RAID if you're on 2.2  :)   On 2.4 it should work.
    
    -- 
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    :   jakob@unthought.net   : And I see the elder races,         :
    :.........................: putrid forms of man                :
    :   Jakob Østergaard      : See him rise and claim the earth,  :
    :        OZ9ABN           : his downfall is at hand.           :
    :.........................:............{Konkhra}...............:
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