On Sun, Mar 28, 2010 at 09:32:02PM -0700, Richard Elling wrote: > This is documented in the ZFS on disk format doc.
Yep, I've been there in the meantime.. ;-) > Use prtvtoc or format to see the beginning of the slice relative to the > beginning of the partition. I dunno how you tell the start of the partition > relative to the physical device. Therein lay my issue. Much discussion of the problem, no simple guidance for end users to see if they are affected, and a bunch of variables (partition types and nesting) to get in the way. At least I now have the basic info that could be scripted into a simple method. > The attached dtrace script is a basic analysis of 4KB aligned starts > (relative to the start of the slice) and 4KB size alignment. Don't be > surprised to see very little alignment due to compression, metadata, > and other oddities. Thanks .. this is useful info for the next level of detail - getting and verifying the alignment of the pool device overall is a first step to make sure these io's don't start out behind the 8-ball. --- Dan.
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