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Where Did that Fine Grained Striping Go?
Starting in version 11gR2 Grid Infrastructure, Oracle changed the default striping method for ONLINELOG from fine to coarse. This change surprised me, as I found it quite by accident. The reason it surprised me is that it is not documented in the 11gR2 new features manual. I actually have not been able to find it documented anywhere. Even worse than that, I have upgraded many of my ASM instances from 11gR1 to 11gR2 and the upgrade process silently changed my existing redo logs from fine to coarse. At first, I thought the must be some explanation, such as I must have recreated my redo logs after the upgrade, or maybe they were always coarse to begin with. I checked many databases, and the ones that were still on 11gR1 ASM were all were using fine grained striping and all of the databases that were upgraded to 11gR2 ASM were all using coarse.
Next week I will be posting a blog entry on this and the results of the performance tests that I performed on the two different methods.
LouisLu
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December 27th, 2011 17:00
Look forward to the post. Don't forget pasting blog entry.
DarrylBSmith
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December 28th, 2011 07:00
Thanks for pointing me to the article. According to it, the change was just a response to increased track sizes due to technology changes. I find this interesting, as the latest flagship product from EMC (VMAX) has a 64 KB track size for Raid 5 and 6 and the recomendation holds true that your stripe size should be 2* track size. My math puts that at 128KB. I have not been able to find Oracle's "storage" system track size, perhaps they changed theirs.
I will publish a link here, when I post the blog entry.
Thanks
Darryl
DarrylBSmith
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January 6th, 2012 13:00
I posted the blog here: Where Did that Fine Grained Striping Go? Please feel free to add your own observations. I was amazed at the performance differences between the different striping methods.
Darryl
slucido
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January 6th, 2012 14:00
Darryl,
Do you mind if we post your blog on the community?
reseach
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January 8th, 2012 22:00
Darry,
good to see your test report, approving 7-12% perforamnce improvment of this changeon 11R2
Eddy
SKT2
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January 18th, 2012 17:00
when you said Oracle's storage did you mean Exadata?
reseach
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January 28th, 2012 18:00
I think this change applies on both of traditional Oracle implementation and EXadata.
Eddy