Oracle FAQ | Your Portal to the Oracle Knowledge Grid |
Home -> Community -> Mailing Lists -> Oracle-L -> Your opinion please...RBS
This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.
------_=_NextPart_001_01C06444.E45A7AA4
Content-Type: text/plain;
charset="iso-8859-1"
Good morning -
I'm reading through some doco about rollback segments and refreshing my memory. I remember a list discussion in the past about 'what is the point of optimal' with rbs's. The book I am reading (Oracle8i DBA Handbook, Oracle Press) states that shrinking to optimal, and extending a rollback segment, are both costly.
Seems to me if you don't have the luxury of a very large tablespace then utilizing optimal is your only way to get rbs's to share disk nicely.
However, if extending and shrinking is that costly, and you have a ton of disk at your disposal, I wonder about making my rbs's fairly large. Optimal right now is 40M (seems large to me). Our main app is more of a hybrid system, so I see wild numbers in v$rollstat - HWM's from 40M to 300M+. Has anyone just created really large rollback segments based on these types of weird sizes?
I also see waits in v$rollstat, and undo waits in v$waitstat. I just bumped up the number of rbs's to 26 based upon a recent HWM of 101 concurrent sessions. My waits are still growing!! Is it totally wild of me to think about adding even more rbs's?? I have more disk than I could ever realistically use in my rbs ts (10G). I am thinking about just doubling the number of rbs's because 1. I don't want to see ANY rbs waits in v$rollstat, v$waitstat and 2. because I've got the disk.
Am I out in left field? Any comments, suggestions, swift KITA's are appreciated. Gracias
Lisa Rutland Koivu
*O*penly *C*ynical & *P*essimistic
Qode.com
4850 North State Road 7
Suite G104
Fort Lauderdale, FL 33319
V: 954.484.3191, x174 F: 954.484.2933 C: 954.658.5849
"The information contained herein does not express the opinion or position of Qode.com and cannot be attributed to or made binding upon Qode.com."
------_=_NextPart_001_01C06444.E45A7AA4
Content-Type: text/html;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =
charset=3Diso-8859-1">
<META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version =
5.5.2650.12">
<TITLE>Your opinion please...RBS</TITLE>
</HEAD>
<BODY>
<P><FONT SIZE=3D2 FACE=3D"Arial">Good morning - </FONT>
</P>
<P><FONT SIZE=3D2 FACE=3D"Arial">I'm reading through some doco about =
rollback segments and refreshing my memory. I remember a list =
discussion in the past about 'what is the point of optimal' with =
rbs's. The book I am reading (Oracle8i DBA Handbook, Oracle =
Press) states that shrinking to optimal, and extending a rollback =
segment, are both costly. </FONT></P>
<P><FONT SIZE=3D2 FACE=3D"Arial">Seems to me if you don't have the =
luxury of a very large tablespace then utilizing optimal is your only =
way to get rbs's to share disk nicely. </FONT></P>
<P><FONT SIZE=3D2 FACE=3D"Arial">However, if extending and shrinking is =
that costly, and you have a ton of disk at your disposal, I wonder =
about making my rbs's fairly large. Optimal right now is 40M =
(seems large to me). Our main app is more of a hybrid system, so =
I see wild numbers in v$rollstat - HWM's from 40M to 300M+. Has =
anyone just created really large rollback segments based on these types =
of weird sizes?</FONT></P>
<P><FONT SIZE=3D2 FACE=3D"Arial">I also see waits in v$rollstat, and =
undo waits in v$waitstat. I just bumped up the number of rbs's to =
26 based upon a recent HWM of 101 concurrent sessions. My waits =
are still growing!! Is it totally wild of me to think about =
adding even more rbs's?? I have more disk than I could ever =
realistically use in my rbs ts (10G). I am thinking about just doubling =
the number of rbs's because 1. I don't want to see ANY rbs waits in =
v$rollstat, v$waitstat and 2. because I've got the disk. </FONT></P>
<P><FONT SIZE=3D2 FACE=3D"Arial">Am I out in left field? Any =
comments, suggestions, swift KITA's are appreciated. =
Gracias</FONT>
</P>
<P><B><FONT SIZE=3D1 FACE=3D"Arial">Lisa Rutland Koivu</FONT></B>
<BR><FONT SIZE=3D1 FACE=3D"Arial">*O*penly *C*ynical & =
*P*essimistic</FONT>
<BR><FONT SIZE=3D1 FACE=3D"Arial">Qode.com</FONT>
<BR><FONT SIZE=3D1 FACE=3D"Arial">4850 North State Road 7</FONT>
<BR><FONT SIZE=3D1 FACE=3D"Arial">Suite G104</FONT>
<BR><FONT SIZE=3D1 FACE=3D"Arial">Fort Lauderdale, FL =
33319</FONT>
</P>
<P><FONT SIZE=3D1 FACE=3D"Arial">V: 954.484.3191, x174</FONT>
<BR><FONT SIZE=3D1 FACE=3D"Arial">F: 954.484.2933 </FONT>
<BR><FONT SIZE=3D1 FACE=3D"Arial">C: 954.658.5849</FONT>
<BR><FONT SIZE=3D1 FACE=3D"Arial"><A HREF=3D"http://www.qode.com" =
TARGET=3D"_blank">http://www.qode.com</A></FONT>
</P>
<P><I><FONT COLOR=3D"#000000" SIZE=3D1 FACE=3D"Arial">"The =
information contained herein does not express the opinion or position =
of Qode.com and cannot be attributed to or made binding upon =
Received on Tue Dec 12 2000 - 08:07:41 CST