Re: Raidframe low I/O for parity rebuild, but when accessed through rraid* devices

["Michael L. Hitch" <mhitch%lightning.msu.montana.edu@localhost>]

On Sat, 13 Jun 2015, Jean-Yves Migeon wrote:

> I think that the slowness is I/O disk bound there: both disks were used 
> elsewhere first, so both have quite different block content. Given that these 
> disks are rather slow (5400 RPM ones), I suppose that they dislike 64k read 
> => compare => then 64k write on one, hence the parity rebuild takes quite 
> some time.

  I'd check if the write cache is disabled on the 2nd disk.  That 
typically makes the writes much slower.  You can use dkctl or atactl to 
check the current cache status and change it.

Mike

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Michael L. Hitch                        mhitch%montana.edu@localhost
Operations Consulting,  Information Technology Center
Montana State University, Bozeman, MT     USA