RE: Filesystem Block Size ? 1K or 4K or 8K ?

From: Mark W. Farnham <>
Date: Wed, 15 Oct 2008 06:01:19 -0400
Message-ID: <>

VS: I'm pretty sure Greg was asking out of actual interest in your reasons, not (as I think you took it from your "WOW") as a backhand slap that you are somehow behind the times.  

So maybe you consider filesystems on VxFS more reliable than ASM, maybe you are just more familiar with them and haven't had a problem with them, or maybe you have some other technical reason for prefering VxFS in your environment for your benchmark. I believe Greg was genuinely asking to hear those reasons. Greg bases his opinions on measured facts, and if you have some facts about your choice I would also like to hear them. That is not a slap, but a genuine question. I'm always interested in learning something.  

Now, as for your benchmark: Measure. Craft (or find) a simple test that simulates the i/o load you expect to see in the benchmark. (If I understand what your "benchmark" exercise is, you are supposed to demonstrate the maximum throughput against a given set of hardware.) I have a guess if had to guess, but you should measure unless someone can produce measurements already made. (I'd guess 8K, just because that means it would have to track fewer units and probably be a small mathmatical advantage as long as your oracle block size is an even multiple of the size you choose. Unless your underlying physical media is ssd, flash, or those fancy new 4K sector drives, it is likely whatever you are looking at is assembled from 512 byte "sectors." If the underlying storage is 4K sector drives, definitely use 4K or 8K, because 1K would be patently stupid in that case and not worth testing.)  

Again, your keyword is "benchmark." If I understand what you are up to, your customer deserves a test of VxFS at the best measured file system block size against ASM.  

Good luck with your test.  



From: [] On Behalf Of VIVEK_SHARMA
Sent: Wednesday, October 15, 2008 3:10 AM To: Greg Rahn
Subject: RE: Filesystem Block Size ? 1K or 4K or 8K ?  

WOW Greg.  

Probably I still belong to the Old Technology of using Mounted Filesystems for Database in a NON-RAC scenario.  


-----Original Message-----
From: Greg Rahn [] Sent: Wednesday, October 15, 2008 3:21 AM To: VIVEK_SHARMA
Subject: Re: Filesystem Block Size ? 1K or 4K or 8K ?  

Out of curiosity, why are you choosing VxFS over ASM?  

On Tue, Oct 14, 2008 at 3:23 AM, VIVEK_SHARMA <> wrote:

> Should the Filesystem (VXFS) Block Size be set to 1K, 4K or 8K? .

> I think it should be 4 K (i.e. Equal to the Page-size)



Greg Rahn

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Received on Wed Oct 15 2008 - 05:01:19 CDT

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