Date: Mon, 04 Apr 2011 14:57:55 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-hardware@freebsd.org Subject: Re: Advanced disk format at WD20EARS: what should "camcontrol identify" show? Message-ID: <incf8j$dn3$1@dough.gmane.org> In-Reply-To: <22830765.20110404101040@serebryakov.spb.ru> References: <22830765.20110404101040@serebryakov.spb.ru>
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On 04/04/2011 08:10, Lev Serebryakov wrote: > Hello, Alexander. > > I'm replacing old WD500AAKS HDDs in my (software) RAID5 with new > WD20EARS, which are advanced format. And speed is terrible. RAID5 > rebuilding shows about 8MiB/s (55MiB/s is typical speed for old AAKSes)... > > I'm affraid, that my HDD is in some strange mode with 512 byte > sectors emulation: With such drives, everything must be 4 KiB-aligned : the RAID stripes, the partitions / slices and the file system / block size. This is the only way to get good performance. If you just replace a non-4K drive in a RAID5 with a 4K drive, it is very likely that there would be alignment problems with that drive.
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