Virident FlashMAX SCM
- From: Anthony Ballo <anthony.ballo@xxxxxxxxxxx>
- To: "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 5 Jun 2012 11:58:31 -0700
Was reading this white paper from Virident today:
Accelerating Oracle Databases and Reducing Storage Complexity and Costs.
Virident FlashMAX SCM as Primary Storage.
Offered at:
http://www.bitpipe.com/data/document.do?res_id37280483_183&srcP53040&asrc=EM_BRU_17570135&uid956921
They are making a point that switching from 8k block size to 4k would reap
performance benefits:
When Oracle data is stored on FlashMAX devices, reducing Oracle database block
size from the default value of 8192 bytes (8KB) to 4096 bytes (4KB) can provide
substantial performance benefits in many applications. With HDDs,
reading/writing 4KB takes essentially the same amount of time as 8KB as most of
the time is spent on moving heads. In contrast, FlashMAX can perform 2x the
amount of IOPS with 4KB block size compared to 8KB block size, or the same
amount of IOPS at lower latencies.
They offered the steps on how to change your block size:
You can set this parameter in several different ways:
1. By adding it to initORACLE_SID.ora file (or changing if the parameter
already exists)
2. By setting the parameter in the SPFILE:
* SQL>alter system set db_block_size@96 scope=spfile;
* SQL>shutdown immediate
* SQL>startup
3. By setting it on Initialization Parameters -> Sizing tab of the DBCA
Last I checked, you could only change the default block size at DB creation.
Sure you can have multiple block sizes supported at the Tablespace level (must
also specify cache sizes) but it's not as simple as changing a init parameter
and bouncing your instance ? otherwise, you will see:
ORA-00209: control file blocksize mismatch, check alert log for more info
Hard to take this white paper seriously or am I missing something?
Anthony
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