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Message-ID: <20070213112527.59eaa504@localhost.localdomain>
Date: Tue, 13 Feb 2007 11:25:27 +0000
From: Alan <alan@...rguk.ukuu.org.uk>
To: "Martin A. Fink" <fink@....mpg.de>
Cc: linux-kernel@...r.kernel.org
Subject: Re: SATA-performance: Linux vs. FreeBSD
> Well they do. The Flash disk I have (SATA-I) is capable of 48 MB/s and this
> value is reached over the whole disk size by windows as well as by FreeBSD.
> See my test results in the first thread.
Ok a flash disk should be more stable
> My Seagate Barracuda Harddisk drive (SATA-II) starts with 76 MB/s and
> decreases linearly to 35 MB/s due to the fact that it has to write to a
> rotating disk. But on a flash disk there is nothing rotating...
The hard disk one isn't guaranteed or stable but the flash especially if
it is aimed at it ought to behave.
> So where is the difference between SATA-I and SATA-II ?
All physical side if they are on the same controller when you do the
tests. Mostly latency,
> And why is FreeBSD able to write with constant rates (the complete 25 GB, all
> with 48+/-0.1 MB/s) but Linux 2.6.18 not ?
Does the FreeBSD fsync sync to media ? Also what controller is being used
here, and do you have EHCI USB support running ?
> With a dedicated (rotating) SATA II device, using the first 70% of disk space
> no problem -- tested ! With a SATA-I device only a problem with Linux 2.6.18
I suspect the SATA-1 itself may not be the decider but something else -
eg the hard disk using NCQ, which would cover up any latency related
problems.
> Journaling of data: you are right, ext2 performs better than ext3.
And ext3 in writeback mode ought in theory (but practice is always
harder ;)) be faster than ext2.
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