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Date: Sat, 27 Aug 2011 11:21:16 +0400
From: Lev Serebryakov <lev@FreeBSD.org>
Organization: FreeBSD Project
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To: Kirk McKusick <mckusick@mckusick.com>
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Cc: fs@freebsd.org
Subject: Re: Strange behaviour of UFS2+SU FS on FreeBSD 8-Stable: dreadful
	perofrmance for old data, excellent for new.
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Hello, Kirk.
You wrote 27 =E0=E2=E3=F3=F1=F2=E0 2011 =E3., 0:52:51:

> Given how much bigger your new filesystem has grown, copying out to
> another filesystem should not be necessary. However, it will likely
  It is theoretically different strategies:
   (a) copy from FS to same FS, mand remove old copy later, force OS
   to choose new place for data.
   (b) copy out, remove, copy in allow OS to use same place.

> be quicker to copy out to another filesystem as you will be using
> two spindles instead of seeking back and forth on one. But before
> doing all that work, try copying one file to ensure that you get the
> expected speedup.
  Yep, three biggest files were speed up significantly.

  I'm going to investigate alter, why it is ony ~180MiB/s, when
theoretically it should be about (90*4) 360MiB/s linear read, and whom
to blame: UFS or geom_raid5 or both :)

--=20
// Black Lion AKA Lev Serebryakov <lev@FreeBSD.org>