Matching storage stripe size with ASM allocation unit?

From: Yong Huang <>
Date: Fri, 23 May 2008 09:26:49 -0700 (PDT)
Message-ID: <>

I heard an Oracle consultant suggest that the storage should be created with stripe size 1M for ASM, because the default ASM allocation unit (probably _asm_ausize) is 1M. He says most shops have much smaller stripe size. I asked since it's too late for the storage team, what if we lower our ASM allocation unit size? He gives no comment except he doesn't recommend.

Now I think about it. The ASM 1M allocation unit is for allocation or deallocation. It can't be I/O chunk size, which is still from db_block_size up to that multiplied by db_file_multiblock_read_count. The ideal stripe size may be typical I/O size dictated by the most frequently run SQL divided by number of disks in the striping setup (or larger than that). The ASM 1M size only plays a role when you create, resize or drop a datafile, not normally done anyway. Comments are welcome.

Yong Huang       

Received on Fri May 23 2008 - 11:26:49 CDT

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