Re: Striping does not increase performance.

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On 12/03/2012 14:34, Jiri Horky wrote:
Hi,

as for alignment, please also check md metadata format version (-e
switch of mdadm). The version that ensures alignment is 1.0, which
places the metadata information to the back of the drive.

As far as I can tell from looking at the source, ever since the 1.x metadata types were introduced (with mdadm 2.0, in August 2005):

* the data offset on 1.1 and 1.2 arrays has always been 4K-aligned,
* the superblock offset for 1.0 arrays has always been 4K-aligned,
* the bitmap offset for all 1.x arrays has always been 4K-aligned.

As of mdadm 3.1.2 (March 2010), the data offset for new 1.1 and 1.2 arrays is always 1MB (2048 sectors), so they're also 1M-aligned.

Cheers,

John.

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