X-MimeOLE: Produced By Microsoft Exchange V6.5
Received: by onstor-exch02.onstor.net 
	id <01C75F64.E6B75FA1@onstor-exch02.onstor.net>; Mon, 5 Mar 2007 13:28:57 -0700
MIME-Version: 1.0
Content-Type: multipart/alternative;
	boundary="----_=_NextPart_001_01C75F64.E6B75FA1"
Content-class: urn:content-classes:message
Subject: RE: mount -sync ?
Date: Mon, 5 Mar 2007 13:28:56 -0700
Message-ID: <BB375AF679D4A34E9CA8DFA650E2B04E02A95C3A@onstor-exch02.onstor.net>
In-Reply-To: <BB375AF679D4A34E9CA8DFA650E2B04E02A95BE5@onstor-exch02.onstor.net>
X-MS-Has-Attach: 
X-MS-TNEF-Correlator: 
Thread-Topic: mount -sync ?
Thread-Index: AcdfNr+OYv3nwWLQQ1GwdvAzfpCMjQAAhWGkAAk9NhAAAX6ZoA==
References: <BB375AF679D4A34E9CA8DFA650E2B04EF30A65@onstor-exch02.onstor.net> <BB375AF679D4A34E9CA8DFA650E2B04E02A95BE5@onstor-exch02.onstor.net>
From: "Steffen Thuemmel" <steffen.thuemmel@onstor.com>
To: "Eric Barrett" <eric.barrett@onstor.com>,
	"Huy Duong" <huy.duong@onstor.com>,
	"dl-se" <dl-se@onstor.com>,
	"dl-cstech" <dl-cstech@onstor.com>

This is a multi-part message in MIME format.

------_=_NextPart_001_01C75F64.E6B75FA1
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

Eric,

You're right - it is RMAN for a 10g RAC. Sorry for the confusion.

If the DB files are located on local storage, can RMAN write the B/U to =
a NFS mounted directory (no_sync) ?

Thanks,
St,

Steffen Thuemmel=20
=20
ONStor
Schleussner Str. 42
D-63263 Neu-Isenburg
Germany
=20
telf.       +49 6102 884 84-0
mobil.     +49 173 673 3434
mail.       steffen.thuemmel@onstor.com
web.       www.onstor.com <http://www.onstor.com/>=20
=20

_____________________________________________
From: Eric Barrett=20
Sent: Montag, 5. M=E4rz 2007 20:50
To: Huy Duong; Steffen Thuemmel; dl-se; dl-cstech
Subject: RE: mount -sync ?


Steffen,

Is this Paragon?  I am the (recent) owner of their performance case, =
4636.

To add to Huy's comments, 'sync' is definitely expected to lower =
performance to the level you have documented on behalf of the customer =
for streaming writes.  I believe your customer is hung up on streaming =
write performance here, which is not completely applicable to the =
database workload he's doing.

I am not aware of a requirement for RMAN to be mounted with 'sync'.  In =
fact, this seems highly unlikely, and a bit of googling turns up no such =
requirement nor any documentation of admins using 'sync' with RMAN on =
NFS.  If the customer believes this, I would definitely challenge him to =
provide documentation stating so.

What definitely *does* require sync is RAC.  The customer has said he is =
using 10g RAC, which requires 'sync' for database log files, as they are =
shared between nodes, and all I/O is expected to be committed to disk by =
the server when the system call returns.

I have already recommended to the customer that, in lieu of 'sync', he =
investigate "direct I/O".  This is supported on any modern Linux kernel =
(RedHat 3.0 and up, for instance), but it does require enabling the =
following init.ora paramter:

FILESYSTEM_IO_OPTIONS=3Ddirectio

Then you mount with =
"hard,vers=3D3,tcp,bg,nointr,rsize=3D32768,wsize=3D32768,noac,timeo=3D600=
".  (Do not deviate from those options -- for instance, do not tweak =
timeo, and do not use UDP instead of TCP.)

Here is a document listing these requirements; they start at page 17:

http://www.oracle.com/technology/products/database/clustering/pdf/EMC_Bes=
tPracticeforOracle.pdf=20

While this is EMC-specific, I know that these recommendations hold true =
for other NFS servers, because they applied to NetApp as well.  In fact, =
I believe NetApp, in combination with Chuck Lever (a Linux kernel =
developer) came up with most of these recommendations.

Finally, about nointr -- my experience with nointr is that enabling it =
only confuses things.  If you interrupt a process (such as oraserver) =
with Ctrl+C or kill, nointr will only delay the termination until a =
non-responsive NFS server comes back.  The only purpose which I know it =
serves is suppressing a bug in older Linux kernels where EAGAIN may =
occasionally be returned from read(2) and write(2) system calls, which =
crashes the database server instance (they're not supposed to return =
EAGAIN when called in a blocking fashion, so Oracle doesn't expect it, =
and thus goes down).


-----Original Message-----
From: Huy Duong=20
Sent: Monday, March 05, 2007 7:25 AM
To: Steffen Thuemmel; dl-se; dl-cstech
Subject: RE: mount -sync ?

Normally, an NFS client delays sending application write requests, =
allowing application processing to overlap with NFS write operations. An =
NFS client only causes an application to wait for writes to complete =
when the application closes or flushes a file. When a client sends write =
operations synchronously, however, the client causes applications to =
wait for each write operation to complete at the server. This results in =
much lower performance.

I am not familiar with RMAN, however what I know is that for databases =
we generally recommend using the nointr flag, but can anyone confirm =
this? This will allow NFS operations to NOT be interrupted while waiting =
for a response from the server.=20
Does this slow down performance?
=20

-----Original Message-----
From: Steffen Thuemmel
Sent: Mon 3/5/2007 6:58 AM
To: dl-se; dl-cstech
Subject: mount -sync ?
=20
I've been called at a customer site to investigate slow performance.

It turned out to be the mount option "sync" which dropped the =
performance. Using sync on a RH 4 client allows a read performance of =
about 2.5 MB/s. Without that option, one client was around 60 MB/s, with =
two clients I could max one IP port at about 120 MB/s.

=20

I know that "sync" impacts the performance, but I could not imagine that =
the penalty is that high.

Here my questions:

-          Does the "sync" option has any impact on the server (the =
BobCat) ?

-          Is the performance penalty introduced by "sync" dependened on =
the client ? Do you have any experience with other clients ?

=20

The customer needs to use "sync" because they want to backup ORACLE DBs =
using  RMAN to a NFS share. RMAN in ORA 10 requires "sync" mounted =
Filesystems.  Do you have any suggestions for workarounds or =
alternatives ?

=20

Thanks for your help,

=20

St.

=20

Steffen Thuemmel=20

Manager Systems Engineering

Central Europe

=20

ONStor

Schleussner Str. 42

D-63263 Neu-Isenburg

Germany

=20

telf.       +49 6102 884 84-0

mobil.     +49 173 673 3434

mail.       steffen.thuemmel@onstor.com =
<mailto:steffen.thuemmel@onstor.com>=20

web.       www.onstor.com <http://www.onstor.com/>=20

=20



------_=_NextPart_001_01C75F64.E6B75FA1
Content-Type: text/html;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =
charset=3Diso-8859-1">
<META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version =
6.5.7652.24">
<TITLE>RE: mount -sync ?</TITLE>
</HEAD>
<BODY>
<!-- Converted from text/rtf format -->

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Calibri">Eric,</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Calibri">You</FONT></SPAN><SPAN LANG=3D"en-us"><FONT =
COLOR=3D"#1F497D" FACE=3D"Calibri">&#8217;</FONT></SPAN><SPAN =
LANG=3D"en-us"><FONT COLOR=3D"#1F497D" FACE=3D"Calibri">re =
right</FONT></SPAN><SPAN LANG=3D"en-us"> <FONT COLOR=3D"#1F497D" =
FACE=3D"Calibri">&#8211;</FONT></SPAN><SPAN LANG=3D"en-us"><FONT =
COLOR=3D"#1F497D" FACE=3D"Calibri"> it</FONT></SPAN><SPAN =
LANG=3D"en-us"> <FONT COLOR=3D"#1F497D" FACE=3D"Calibri">is RMAN for a =
10g RAC.</FONT></SPAN><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Calibri"> Sorry for the confusion.</FONT></SPAN><SPAN =
LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Calibri">If the DB files are located on local =
storage</FONT></SPAN><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Calibri">, can RMAN write the B/U to a NFS =
mounted</FONT></SPAN><SPAN LANG=3D"en-us"> <FONT COLOR=3D"#1F497D" =
FACE=3D"Calibri">directory</FONT></SPAN><SPAN LANG=3D"en-us"><FONT =
COLOR=3D"#1F497D" FACE=3D"Calibri"></FONT></SPAN><SPAN LANG=3D"en-us"> =
<FONT COLOR=3D"#1F497D" FACE=3D"Calibri">(no_sync) ?</FONT></SPAN><SPAN =
LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Calibri">Thanks,</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Calibri">St,</FONT></SPAN><SPAN LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><B><SPAN =
LANG=3D"en-us"><FONT COLOR=3D"#1F497D" FACE=3D"Arial">Steffen =
Thuemmel</FONT></SPAN></B><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"> =
</SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">=A0</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><B><SPAN =
LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">ONStor</FONT></SPAN></B><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">Schleussner Str. 42</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">D-63263 Neu-Isenburg</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">Germany</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">=A0</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><B><SPAN =
LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">telf.</FONT></SPAN></B><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><B><SPAN LANG=3D"en-us"><FONT =
COLOR=3D"#1F497D" SIZE=3D2 =
FACE=3D"Arial">=A0=A0=A0=A0=A0=A0</FONT></SPAN></B><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><B><SPAN LANG=3D"en-us"> <FONT =
COLOR=3D"#1F497D" SIZE=3D1 FACE=3D"Arial">+49 6102 884 =
84-0</FONT></SPAN></B><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><B><SPAN =
LANG=3D"en-us"><FONT COLOR=3D"#1F497D" FACE=3D"Arial">mobil. =
=A0=A0=A0</FONT></SPAN></B><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><B><SPAN =
LANG=3D"en-us"> <FONT COLOR=3D"#1F497D" SIZE=3D1 FACE=3D"Arial">+49 173 =
673 3434</FONT></SPAN></B><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><B><SPAN =
LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">mail.=A0=A0=A0=A0=A0=A0</FONT></SPAN></B><SPAN =
LANG=3D"en-us"> </SPAN><A =
HREF=3D"mailto:steffen.thuemmel@onstor.com"><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B><U></U></B></SPAN><B><U><SPAN LANG=3D"en-us"><FONT =
COLOR=3D"#0000FF" =
FACE=3D"Arial">steffen.thuemmel@onstor.com</FONT></SPAN></U></B><SPAN =
LANG=3D"en-us"></SPAN></A><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><B><SPAN =
LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">web.=A0=A0=A0=A0=A0=A0</FONT></SPAN></B><SPAN =
LANG=3D"en-us"> </SPAN><A HREF=3D"http://www.onstor.com/"><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B><U></U></B></SPAN><B><U><SPAN LANG=3D"en-us"><FONT =
COLOR=3D"#0000FF" =
FACE=3D"Arial">www.onstor.com</FONT></SPAN></U></B><SPAN =
LANG=3D"en-us"></SPAN></A><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT COLOR=3D"#1F497D" =
FACE=3D"Arial">=A0</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Tahoma">_____________________________________________<BR>
</FONT></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B><FONT SIZE=3D2 =
FACE=3D"Tahoma">From:</FONT></B></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Eric Barrett<BR>
</FONT></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B><FONT SIZE=3D2 =
FACE=3D"Tahoma">Sent:</FONT></B></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Montag, 5. M=E4rz 2007 20:50<BR>
</FONT></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B><FONT SIZE=3D2 =
FACE=3D"Tahoma">To:</FONT></B></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Huy Duong; Steffen Thuemmel; dl-se; dl-cstech<BR>
</FONT></SPAN><SPAN LANG=3D"en-us"><B></B></SPAN><SPAN =
LANG=3D"en-us"><B></B></SPAN><SPAN LANG=3D"en-us"><B><FONT SIZE=3D2 =
FACE=3D"Tahoma">Subject:</FONT></B></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Tahoma"> RE: mount -sync =
?</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">Steffen,</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Is this =
Paragon?&nbsp; I am the (recent) owner of their performance case, =
4636.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">To add =
to Huy's comments, 'sync' is definitely expected to lower performance to =
the level you have documented on behalf of the customer for streaming =
writes.&nbsp; I believe your customer is hung up on streaming write =
performance here, which is not completely applicable to the database =
workload he's doing.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">I am not =
aware of a requirement for RMAN to be mounted with 'sync'.&nbsp; In =
fact, this seems highly unlikely, and a bit of googling turns up no such =
requirement nor any documentation of admins using 'sync' with RMAN on =
NFS.&nbsp; If the customer believes this, I would definitely challenge =
him to provide documentation stating so.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">What =
definitely *does* require sync is RAC.&nbsp; The customer has said he is =
using 10g RAC, which requires 'sync' for database log files, as they are =
shared between nodes, and all I/O is expected to be committed to disk by =
the server when the system call returns.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">I have =
already recommended to the customer that, in lieu of 'sync', he =
investigate &quot;direct I/O&quot;.&nbsp; This is supported on any =
modern Linux kernel (RedHat 3.0 and up, for instance), but it does =
require enabling the following init.ora paramter:</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">FILESYSTEM_IO_OPTIONS=3Ddirectio</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Then you =
mount with =
&quot;hard,vers=3D3,tcp,bg,nointr,rsize=3D32768,wsize=3D32768,noac,timeo=3D=
600&quot;.&nbsp; (Do not deviate from those options -- for instance, do =
not tweak timeo, and do not use UDP instead of TCP.)</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Here is =
a document listing these requirements; they start at page =
17:</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"></SPAN><A =
HREF=3D"http://www.oracle.com/technology/products/database/clustering/pdf=
/EMC_BestPracticeforOracle.pdf"><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><U><FONT COLOR=3D"#0000FF" =
SIZE=3D2 =
FACE=3D"Arial">http://www.oracle.com/technology/products/database/cluster=
ing/pdf/EMC_BestPracticeforOracle.pdf</FONT></U></SPAN><SPAN =
LANG=3D"en-us"></SPAN></A><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial"> </FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">While =
this is EMC-specific, I know that these recommendations hold true for =
other NFS servers, because they applied to NetApp as well.&nbsp; In =
fact, I believe NetApp, in combination with Chuck Lever (a Linux kernel =
developer) came up with most of these recommendations.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Finally, =
about nointr -- my experience with nointr is that enabling it only =
confuses things.&nbsp; If you interrupt a process (such as oraserver) =
with Ctrl+C or kill, nointr will only delay the termination until a =
non-responsive NFS server comes back.&nbsp; The only purpose which I =
know it serves is suppressing a bug in older Linux kernels where EAGAIN =
may occasionally be returned from read(2) and write(2) system calls, =
which crashes the database server instance (they're not supposed to =
return EAGAIN when called in a blocking fashion, so Oracle doesn't =
expect it, and thus goes down).</FONT></SPAN></P>
<BR>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">-----Original Message-----</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">From: =
Huy Duong </FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Sent: =
Monday, March 05, 2007 7:25 AM</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">To: =
Steffen Thuemmel; dl-se; dl-cstech</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Subject: =
RE: mount -sync ?</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">Normally, an NFS client delays sending application write =
requests, allowing application processing to overlap with NFS write =
operations. An NFS client only causes an application to wait for writes =
to complete when the application closes or flushes a file. When a client =
sends write operations synchronously, however, the client causes =
applications to wait for each write operation to complete at the server. =
This results in much lower performance.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">I am not =
familiar with RMAN, however what I know is that for databases we =
generally recommend using the nointr flag, but can anyone confirm this? =
This will allow NFS operations to NOT be interrupted while waiting for a =
response from the server. </FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Does =
this slow down performance?</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">-----Original Message-----</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">From: =
Steffen Thuemmel</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Sent: =
Mon 3/5/2007 6:58 AM</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">To: =
dl-se; dl-cstech</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Subject: =
mount -sync ?</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">I've =
been called at a customer site to investigate slow =
performance.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">It =
turned out to be the mount option &quot;sync&quot; which dropped the =
performance. Using sync on a RH 4 client allows a read performance of =
about 2.5 MB/s. Without that option, one client was around 60 MB/s, with =
two clients I could max one IP port at about 120 MB/s.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">I know =
that &quot;sync&quot; impacts the performance, but I could not imagine =
that the penalty is that high.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Here my =
questions:</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
Does the &quot;sync&quot; option has any impact on the server (the =
BobCat) ?</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
Is the performance penalty introduced by &quot;sync&quot; dependened on =
the client ? Do you have any experience with other clients =
?</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">The =
customer needs to use &quot;sync&quot; because they want to backup =
ORACLE DBs using&nbsp; RMAN to a NFS share. RMAN in ORA 10 requires =
&quot;sync&quot; mounted Filesystems.&nbsp; Do you have any suggestions =
for workarounds or alternatives ?</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Thanks =
for your help,</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">St.</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Steffen =
Thuemmel </FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Manager =
Systems Engineering</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">Central =
Europe</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">ONStor</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">Schleussner Str. 42</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 FACE=3D"Arial">D-63263 =
Neu-Isenburg</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">Germany</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">telf.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; +49 6102 884 =
84-0</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">mobil.&nbsp;&nbsp;&nbsp;&nbsp; +49 173 673 =
3434</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">mail.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
steffen.thuemmel@onstor.com &lt;</FONT></SPAN><SPAN =
LANG=3D"en-us"></SPAN><A =
HREF=3D"mailto:steffen.thuemmel@onstor.com"><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"><U><FONT COLOR=3D"#0000FF" SIZE=3D2 =
FACE=3D"Arial">mailto:steffen.thuemmel@onstor.com</FONT></U></SPAN><SPAN =
LANG=3D"en-us"></SPAN></A><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&gt; </FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">web.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT></SPAN><SPA=
N LANG=3D"en-us"> </SPAN><A HREF=3D"file://www.onstor.com"><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"><U><FONT COLOR=3D"#0000FF" SIZE=3D2 =
FACE=3D"Arial">www.onstor.com</FONT></U></SPAN><SPAN =
LANG=3D"en-us"></SPAN></A><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial"> &lt;</FONT></SPAN><SPAN LANG=3D"en-us"></SPAN><A =
HREF=3D"http://www.onstor.com/"><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><U><FONT COLOR=3D"#0000FF" =
SIZE=3D2 FACE=3D"Arial">http://www.onstor.com/</FONT></U></SPAN><SPAN =
LANG=3D"en-us"></SPAN></A><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&gt; </FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"><FONT SIZE=3D2 =
FACE=3D"Arial">&nbsp;</FONT></SPAN></P>

<P DIR=3DLTR><SPAN LANG=3D"en-us"></SPAN><SPAN =
LANG=3D"en-us"></SPAN><SPAN LANG=3D"en-us"></SPAN></P>

</BODY>
</HTML>
------_=_NextPart_001_01C75F64.E6B75FA1--
