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Oracle Block size and VMFS block size
Based on my observation, most of OTLP ORA database’s block size is 4K,8K; VMFS’s block size is 1-8M, which depends on VMFS version and datastore capacity, the ratio of VMFS block size: Oracle Block size is over 250X. therefore I am concerning about IO efficiency and if Oracle IO in VM would generate lots of VMFS IO, which might cause some performance issues.
Thanks,
Eddy
dba_hba
63 Posts
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September 5th, 2011 02:00
Eddy
"The VMFS block size is not used for guest read/writes."
See this document
http://communities.vmware.com/docs/DOC-11458
under the section Understanding VMFS block size
and explained by the following paragraph
"When your Linux/Windows/Solaris guest reads/writes data, it does so in blocks and these blocks are usually around 64KB. For example, when your guest issues a SCSI read, then nothing happens to the VMFS at all - the read is "passed through" by the vmkernel straight to the SAN LUN.
VMFS does not get in the way of your guest read/writes, it does not do any kind of caching, the VMFS block size is irrelevant for guest I/O.
Where the VMFS block size is important is when fixing the maximum VMDK size"
Hope this helps
Allan
taceyr
98 Posts
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August 29th, 2011 05:00
Good morning, Eddy!
Oracle works great on VMware. I found a great blog post (granted from 2007 but it's still referenced on VMware's Solutions page and after reviewing it the tech doesn't seem to have made any changes which would invalidate the statements). Take a read at http://blogs.vmware.com/performance/2007/11/ten-reasons-why.html. And for something more recent, The Virtual Geek blog has a post here: http://virtualgeek.typepad.com/virtual_geek/2011/07/even-more-reasons-to-run-oracle-on-vmware.html. This one is from our very own VP, Chad Sakac. It talks about performance, cost, and availability.
Let me know if this helps to answer your concern.
R.
reseach
225 Posts
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September 6th, 2011 03:00
Thanks both of Allanr and Rob. I got the point