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Re: [linux-lvm] I:LVM Raw Oracle 9i RAC



On Fri, Sep 19, 2003 at 01:12:00PM +0200, Bernat Covacho, Jose Maria wrote:
> Hi Heinz
> 
> Yes. We see the same degradation using Oracle

Hmmm, I can only assume that the stripe units you choosed (it is a striped LV,
right ?) are suboptimal with raw devices in your case.

Because laying out striped LVs in the best performing way is very
application specific, you may want to try different stripe sizes
(lvcreate's -I option) and different numbers of stripes (-i option).

I am not aware of any Oracle recommendations WRT using striped LVs.

Anyone from Oracle able to comment on this ?

Regards,
Heinz    -- The LVM Guy --

> 
> Oracle without LVM takes 15 sec to read 8 GB , and Oracle with lvm takes 50-60 sec
> 
> Thank´s
> 
> Bernat
> 
> -----Mensaje original-----
> De: Heinz J . Mauelshagen [mailto:mauelshagen sistina com] 
> Enviado el: viernes, 19 de septiembre de 2003 12:40
> Para: linux-lvm sistina com
> Asunto: Re: [linux-lvm] I:LVM Raw Oracle 9i RAC
> 
> 
> dd is no good tool to do such performance numbers.
> Do you see any degradations in Oracle compared to non-LVM raw devices ?
> 
> Regards,
> Heinz    -- The LVM Guy --
> 
> 
> On Tue, Sep 16, 2003 at 01:30:05PM +0200, Bernat Covacho, Jose Maria wrote:
> > Hello, we have a RedHat Avanced Server 2.1 with kernel version 2.4.9-e.12smp and we use lvm version 1.0.3 (yes I know that the latest "one" version is 1.0.7). I think that the version 2 is too much advanced for us. 
> >  
> > We have a very strange problem with lvm, oracle and raw devices. If we take a logical volume manager and test it with a simple dd we get:
> >  
> > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> > time dd if=/dev/MKTP/strip32 of=/dev/null bs=512k count=2048 
> > 2048+0 registros leídos
> > 2048+0 registros escritos
> >  
> > real    0m13.394s
> > user    0m0.000s
> > sys     0m6.090s
> > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> >  
> > Ok, It works fine, we have 1Gbyte in 13 seconds.
> >  
> > Now we bind this logical volume to a raw device
> >  
> > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> > raw /dev/MKTP/strip32 /dev/raw/raw15
> > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> >  
> > and we try with this:
> >  
> > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> > time dd if=/dev/raw/raw15  of=/dev/null bs=512k count=2048 
> > 2048+0 registros leídos
> > 2048+0 registros escritos
> >  
> > real    0m14.828s
> > user    0m0.020s
> > sys     0m6.180s
> > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> >  
> > The same time, more or less, all it's ok. 
> >  
> > Now we want use this raw (raw15) with oracle. We create a oracle tablespace put data into. We can access it through oracle.
> >  
> > We stop oracle. Now we repeat the same dd:
> >  
> > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> > time dd if=/dev/raw/raw15 of=/dev/null bs=512k count=2048
> > 2048+0 registros leídos
> > 2048+0 registros escritos
> >  
> > real    0m48.971s
> > user    0m0.010s
> > sys     0m11.590s
> > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> >  
> > Now we have 48 seconds, why?, The only one difference is the tablespace creation.
> >  
> > We try the same process without lvm and we have the same good time in three cases.
> >  
> > There are some problem with lvm, raw and oracle?
> > How can I avoid this?
> >  
> > Thanks in advanced
> >  
> >  
> >  
> >  
> >  
> > ========================================
> > 
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> > 
> >  This information is private and confidential and intended for the recipient only. If you are not the intended recipient of this message you are hereby notified that any review it and notify the sender immediately, dissemination, distribution or copying of this message is strictly prohibited.  This communication is for information purposes only and should not be regarded as an official statement from gasNatural Group. Email transmission cannot be guaranteed to be secure.  Therefore, we do not represent that this information is complete or accurate and it should not be relied upon as such.All information is subject to change without notice. This email has been scanned by our Antivirus system
> > 
> 
> *** Software bugs are stupid.
>     Nevertheless it needs not so stupid people to solve them ***
> 
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 
> Heinz Mauelshagen                                 Sistina Software Inc.
> Senior Consultant/Developer                       Am Sonnenhang 11
>                                                   56242 Marienrachdorf
>                                                   Germany
> Mauelshagen Sistina com                           +49 2626 141200
>                                                        FAX 924446
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm sistina com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> ========================================
> 
> Esta información es privada y confidencial y está dirigida únicamente a su destinatario. Si usted no es el destinatario original de este mensaje y por este medio pudo acceder a dicha información por favor elimine el mensaje y notifique el envío erróneo al remitente. La distribución o copia de este mensaje está estrictamente prohibida. Esta comunicación es sólo para propósitos de información y no debería ser considerada como una declaración oficial del Grupo gasNatural. La transmisión de e-mails no garantiza que el correo electrónico sea seguro. Por consiguiente, no manifestamos que esta información sea completa o precisa. Toda información está sujeta a alterarse sin previo aviso. Este Correo Electrónico ha sido procesado por nuestro sistema de Antivirus corporativo 
> 
>  This information is private and confidential and intended for the recipient only. If you are not the intended recipient of this message you are hereby notified that any review it and notify the sender immediately, dissemination, distribution or copying of this message is strictly prohibited.  This communication is for information purposes only and should not be regarded as an official statement from gasNatural Group. Email transmission cannot be guaranteed to be secure.  Therefore, we do not represent that this information is complete or accurate and it should not be relied upon as such.All information is subject to change without notice. This email has been scanned by our Antivirus system
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm sistina com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen Sistina com                           +49 2626 141200
                                                       FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-



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