Oracle often seems to recommend 1:1 (which is often not enough, especially with DISM). You don't even have 1:1.
Solaris also uses free memory as part of its swap space allocation. Locked memory, such as ISM/DISM eats free memory, and so reduces your available swap further. You should confirm that DISM is off by running "pmap -x" against a process from each of your DBs (the shared memory should appear as "ism") Commands like "swap -s" and good ol' "vmstat 5" are useful for monitoring swap. You should also run "echo :: memstat | mdb -k" from time to time to get a feel for hiw your RAM is being used" (on large machines, I've seen it take up to an hour to complete, and it will hig a CPU for the duration, but it seems to have little other impact on the system). On 29 Oct 2010, at 23:37, Robin Cotgrove <ro...@rjcnet.co.uk> wrote: >> This is what Oracle says about swap for 11gR2. The >> comment about >> subtracting ISM is not >> correct. A simple test shows that ISM does consume >> swap (even if it's >> not DISM). Think >> about what happens when a memory segment is created >> (before it goes to >> ISM), if someone >> happens to attach in non-ISM mode and when everyone >> detaches from the >> segment and it >> ceases to be ISM). In the first and last stage swap >> space is *required* >> and the VM system >> reserves the space needed when the segment is first >> created. > > I agree with you. In our case disabling the use of DISM really helped to make > the platform more stable and helped with overall memory usage. > > By the way, we using Oracle 10.2.0.4. No use of Oracle 11gR2 yet. > > We have 192GB of physical memory and 96GB of swap device. The SGA/PGA sizes > of all the Oracle DB's fit well within the 192GB leaving a consistent ~50GB > spare. Memory consumption stays stable on the platform and doesn't go up and > down. This is the nature of the Oracle DB's allocating memory at start-up. > >> >> I would be cautious about Oracle assurances... > > Yep >> >> Jim >> --- >> >>> go to the following for full list of available >> oracle book. >>> http://www.oracle.com/pls/db112/homepage >>> >>> which links to the 11gr2 install guide >>> Db install guides >>> >> http://www.oracle.com/pls/db112/portal.portal_db?selec >> ted=11&frame= >>> >>> which links to the following section on memory >>> >> http://download.oracle.com/docs/cd/E11882_01/install.1 >> 12/e17163/pre_install.htm#sthref62 >>> >>> >>> >>> ------ >>> 2.2.1 Memory Requirements >>> >>> The following are the memory requirements for >> installing Oracle >>> Database 11g Release 2. >>> >>> * >>> >>> At least 4 GB of RAM >>> >>> To determine the RAM size, enter the >> following command: >>> >>> # /usr/sbin/prtconf | grep "Memory size" >>> >>> If the size of the RAM is less than the required >> size, then you must >>> install more memory before continuing. >>> >>> * >>> >>> The following table describes the >> relationship between installed >>> RAM and the configured swap space recommendation: >>> >>> Note: >>> On Solaris, if you use non-swappable memory, >> like ISM, then you >>> should deduct the memory allocated to this space >> from the available >>> RAM before calculating swap space. >>> RAM Swap Space >>> Between 4 GB and 16 GB Equal to the size >> of RAM >>> More than 16 GB 16 GB >> >> >> >> On 10/29/2010 2:01 PM, Jim Mauro wrote: >>> Thanks Mike. Good point on the script. >>> >>> Indeed, use of speculative tracing would be a >> better >>> fit here. I'll see if I can get something together >> and >>> send it out. >>> >>> Thanks, >>> /jim >>> >>> On Oct 29, 2010, at 4:45 PM, Mike Gerdts wrote: >>> >>>> On Fri, Oct 29, 2010 at 2:50 PM, Robin >> Cotgrove<ro...@rjcnet.co.uk> wrote: >>>>> Sorry guys. Swap is not the issue. We've had this >> confirmed by Oracle and I can clearly see there is >> 96GB of swap awailable on the system and ~50GB of >> main memory. >>>> By who at Oracle? Not everyone is equally >> qualified. I would tend to >>>> trust Jim Mauro (who co-wrote the books[1] on >> Solaris internals, >>>> performance,& dtrace) over most of the people you >> will get to through >>>> normal support channels. >>>> >>>> 1. http://www.amazon.com/Jim-Mauro/e/B001ILM8NC/ >>>> >>>> How do you know that available swap doesn't >> momentarily drop? I've >>>> run into plenty of instances where a system has >> tens of gigabytes of >>>> free memory but is woefully short on reservable >> swap (virtual memory, >>>> as Jim approximates). Usually "vmstat 1" is >> helpful in observing >>>> spikes, but as I said before this could miss very >> short spikes. If >>>> you've already done this to see that swap is >> unlikely to be an issue, >>>> knowing that would be useful to know. If you are >> measuring the amount >>>> of reservable swap with "swap -l", you are doing >> it wrong. >>>> >>>> I do agree that there can be other shortfalls that >> can cause this. >>>> This may call for speculative tracing of stacks >> across the fork entry >>>> and return calls, displaying results only when the >> fork fails with >>>> EAGAIN. Jim's second script is similar to what I >> suggest, except that >>>> it doesn't show the code path taken between >> syscall::forksys:entry and >>>> syscall::forksys:return. >>>> >>>> Also, I would be a little careful running the >> second script as is for >>>> long periods of time if you have a lot of forksys >> activity with unique >>>> stacks. I think that as it is @ks may grow rather >> large over time >>>> because the successful forks are not cleared. >>>> >>>> -- >>>> Mike Gerdts >>>> http://mgerdts.blogspot.com/ >>>> _______________________________________________ >>>> dtrace-discuss mailing list >>>> dtrace-discuss@opensolaris.org >>> _______________________________________________ >>> dtrace-discuss mailing list >>> dtrace-discuss@opensolaris.org >> >> >> -- >> Oracle <http://www.oracle.com> >> James Litchfield | Senior Consultant >> Phone: +1 4082237059 <tel:+1%204082237059> | Mobile: >> +1 4082180790 >> <tel:+1%204082180790> >> Oracle Oracle ACS >> California >> Green Oracle <http://www.oracle.com/commitment> >> Oracle is committed to >> developing practices and products that help protect >> the environment >> <div id="jive-html-wrapper-div"> >> >> This is what Oracle says about swap for 11gR2. >> The comment about >> subtracting ISM is not<br> >> correct. A simple test shows that ISM does consume >> swap (even if >> it's not DISM). Think<br> >> about what happens when a memory segment is created >> (before it goes >> to ISM), if someone<br> >> happens to attach in non-ISM mode and when everyone >> detaches from >> the segment and it<br> >> ceases to be ISM). In the first and last stage swap >> space is >> *required* and the VM system<br> >> reserves the space needed when the segment is first >> created.<br> >> <br> >> I would be cautious about Oracle assurances...<br> >> <br> >> Jim<br> >> ---<br> >> <br> >> <blockquote type="cite">go to the following for >> full list of >> available oracle book. <br> >> <a moz-do-not-send="true" >> class="moz-txt-link-freetext" >> >> ref="http://www.oracle.com/pls/db112/homepage";>http:// >> www.oracle.com/pls/db112/homepage</a> >> <br> >> <br> >> which links to the 11gr2 install guide <br> >> Db install guides <br> >> <a moz-do-not-send="true" >> class="moz-txt-link-freetext" >> ref="http://www.oracle.com/pls/db112/portal.portal_db? >> selected=11&frame=">http://www.oracle.com/pls/db11 >> 2/portal.portal_db?selected=11&frame=</a> >> <br> >> <br> >> which links to the following section on memory >> <br> >> <a moz-do-not-send="true" >> class="moz-txt-link-freetext" >> ref="http://download.oracle.com/docs/cd/E11882_01/inst >> all.112/e17163/pre_install.htm#sthref62">http://downlo >> ad.oracle.com/docs/cd/E11882_01/install.112/e17163/pre >> _install.htm#sthref62</a> >> <br> >> <br> >> <br> >> ------ <br> >> 2.2.1 Memory Requirements <br> >> <br> >> The following are the memory requirements for >> installing Oracle >> Database 11g Release 2. <br> >> <br> >> * <br> >> <br> >> At least 4 GB of >> RAM <br> >> <br> >> To determine the RAM >> size, enter the following command: <br> >> <br> >> # /usr/sbin/prtconf | grep "Memory size" <br> >> <br> >> If the size of the RAM is less than the required >> size, then you >> must install more memory before continuing. <br> >> <br> >> * <br> >> <br> >> The following >> table describes the relationship between >> installed RAM and the configured swap space >> recommendation: <br> >> <br> >> Note: <br> >> On Solaris, if >> you use non-swappable memory, like ISM, then >> you should deduct the memory allocated to this >> space from the >> available RAM before calculating swap space. >> <br> >> >> RAM Swap Space <br> >> Between 4 GB and >> 16 GB Equal to the size of >> RAM <br> >> More than 16 >> GB 16 GB </blockquote> >> <br> >> <br> >> <br> >> On 10/29/2010 2:01 PM, Jim Mauro wrote: >> <blockquote >> >> ite="mid:45d35217-5bfa-40b3-9bb4-cbdc52813...@oracle.c >> om" >> type="cite"> >> <pre wrap="">Thanks Mike. Good point on the script. >> >> Indeed, use of speculative tracing would be a better >> fit here. I'll see if I can get something together >> and >> send it out. >> >> Thanks, >> /jim >> >> On Oct 29, 2010, at 4:45 PM, Mike Gerdts wrote: >> >> </pre> >> <blockquote type="cite"> >> <pre wrap="">On Fri, Oct 29, 2010 at 2:50 PM, Robin >> Cotgrove <a class="moz-txt-link-rfc2396E" >> href="mailto:ro...@rjcnet.co.uk";><ro...@rjcnet.co. >> k></a> wrote: >> </pre> >> <blockquote type="cite"> >> <pre wrap="">Sorry guys. Swap is not the issue. >> We've had this confirmed by Oracle and I can clearly >> see there is 96GB of swap awailable on the system >> and ~50GB of main memory. >> /pre> >> </blockquote> >> <pre wrap=""> >> By who at Oracle? Not everyone is equally qualified. >> I would tend to >> rust Jim Mauro (who co-wrote the books[1] on Solaris >> internals, >> performance, & dtrace) over most of the people >> you will get to through >> normal support channels. >> >> 1. <a class="moz-txt-link-freetext" >> href="http://www.amazon.com/Jim-Mauro/e/B001ILM8NC/";>h >> ttp://www.amazon.com/Jim-Mauro/e/B001ILM8NC/</a> >> >> How do you know that available swap doesn't >> momentarily drop? I've >> run into plenty of instances where a system has tens >> of gigabytes of >> free memory but is woefully short on reservable swap >> (virtual memory, >> as Jim approximates). Usually "vmstat 1" is helpful >> in observing >> spikes, but as I said before this could miss very >> short spikes. If >> you've already done this to see that swap is unlikely >> to be an issue, >> knowing that would be useful to know. If you are >> measuring the amount >> of reservable swap with "swap -l", you are doing it >> wrong. >> >> I do agree that there can be other shortfalls that >> can cause this. >> This may call for speculative tracing of stacks >> across the fork entry >> and return calls, displaying results only when the >> fork fails with >> EAGAIN. Jim's second script is similar to what I >> suggest, except that >> it doesn't show the code path taken between >> syscall::forksys:entry and >> syscall::forksys:return. >> >> Also, I would be a little careful running the second >> script as is for >> long periods of time if you have a lot of forksys >> activity with unique >> stacks. I think that as it is @ks may grow rather >> large over time >> because the successful forks are not cleared. >> >> -- >> Mike Gerdts >> <a class="moz-txt-link-freetext" >> href="http://mgerdts.blogspot.com/";>http://mgerdts.blo >> gspot.com/</a> >> _______________________________________________ >> dtrace-discuss mailing list >> <a class="moz-txt-link-abbreviated" >> href="mailto:dtrace-discuss@opensolaris.org";>dtrace-di >> sc...@opensolaris.org</a> >> </pre> >> </blockquote> >> <pre wrap=""> >> _______________________________________________ >> dtrace-discuss mailing list >> <a class="moz-txt-link-abbreviated" >> href="mailto:dtrace-discuss@opensolaris.org";>dtrace-di >> sc...@opensolaris.org</a> >> </pre> >> </blockquote> >> <br> >> <br> >> <div class="moz-signature">-- <br> >> <a href="http://www.oracle.com"; >> target="_blank"><img >> src="cid:part1.03060504.05020101@oracle.com" >> alt="Oracle" >> border="0" height="26" width="114"></a><br> >> nt size="2" color="#666666" face="Verdana, Arial, >> Helvetica, >> sans-serif">James Litchfield | Senior >> Consultant<br> >> Phone: <a href="tel:+1%204082237059">+1 >> 4082237059</a> | >> Mobile: <a href="tel:+1%204082180790">+1 >> 4082180790</a> <br> >> <font color="#ff0000">Oracle</font> Oracle >> ACS<br> >> California </font> >> r> >> <a href="http://www.oracle.com/commitment"; >> target="_blank"><img >> src="cid:part2.07030704.04000406@oracle.com" >> alt="Green >> Oracle" align="abscenter" border="0" >> height="28" width="44"></a> >> <font size="1" color="#4b7d42" face="Verdana, >> Arial, Helvetica, >> sans-serif">Oracle is committed to developing >> practices and >> products that help protect the >> environment</font> >> <!-- This signature was generated by the >> MyDesktop Oracle Business Signature utility version >> 3.6.0 --> >> <!-- Visit http://mydesktop.oracle.com/ and try >> it for yourself --> >> </div> >> </div>_______________________________________________ >> dtrace-discuss mailing list >> dtrace-discuss@opensolaris.org > -- > This message posted from opensolaris.org > _______________________________________________ > dtrace-discuss mailing list > dtrace-discuss@opensolaris.org _______________________________________________ dtrace-discuss mailing list dtrace-discuss@opensolaris.org
