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Re: What is a recommended XFS sector size for hybrid (512e) advanced for

To: Eric Sandeen <sandeen@xxxxxxxxxxx>
Subject: Re: What is a recommended XFS sector size for hybrid (512e) advanced format hard drives?
From: Chris Murphy <lists@xxxxxxxxxxxxxxxxx>
Date: Tue, 6 Jan 2015 23:01:51 -0700
Cc: Chris Murphy <lists@xxxxxxxxxxxxxxxxx>, "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>
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Sender: chris@xxxxxxxxxxxxxxxxx
On Tue, Jan 6, 2015 at 10:31 PM, Eric Sandeen <sandeen@xxxxxxxxxxx> wrote:
> On 1/6/15 1:55 PM, Chris Murphy wrote:
>> What's sectsz= used for? Historically this would be sectsz=512,
>> bsize=4096 before AF hard drives appeared. So is sectsz used for
>> optimizing sub blocksize changes? e.g. if only 50 bytes needs
>> changing, the fs doesn't need to read modify and write the entire 4096
>> block, just change the affected sector?
>
> Nope, filesystem data blocks are always fully written, but the sector
> size is i.e. the minimum _log_ IO size.

So maybe the people reporting performance problems with sectsz=512 on
AF drives compared to manually specifying 4096 bytes, have a high
metadata workload with older AF drives and are getting lot of in-drive
RMW...


-- 
Chris Murphy

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