XFS: Abysmal write performance because of excessive seeking (allocation groups to blame?)

[Stefan Ring]

> As to this, in theory even having split the files among 4 AGs,
> the upload from system RAM to host adapter RAM and then to disk
> could happen by writing first all the dirty blocks for one AG,
> then a long seek to the next AG, and so on, and the additional
> cost of 3 long seeks would be negligible.

Yes, that’s exactly what I had in mind, and what prompted me to write
this post. It would be about 10 times as fast. That’s what bothers me
so much.