Date: Fri, 1 Feb 2013 15:04:30 -0000 From: "Steven Hartland" <killing@multiplay.co.uk> To: "Wojciech Puchar" <wojtek@wojtek.tensor.gdynia.pl>, <freebsd-hackers@freebsd.org> Subject: Re: HDD write cache Message-ID: <DF4C0697C59747BEBE5DF564E0B934EB@multiplay.co.uk> References: <alpine.BSF.2.00.1302011524480.43260@wojtek.tensor.gdynia.pl>
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Looking at the cam ata code I can't see how those values would do
anything after booting.
I suspect they should be loader only tunables with the current code
and cant be changed on the fly for a disk that's already been
registered.
Try setting the values in /boot/loader.conf if you haven't already?
You can check the actual status of the disk itself using:-
camcontrol identify ada0
Regards
Steve
----- Original Message -----
From: "Wojciech Puchar" <wojtek@wojtek.tensor.gdynia.pl>
To: <freebsd-hackers@freebsd.org>
Sent: Friday, February 01, 2013 2:26 PM
Subject: HDD write cache
> after reading quite recent topics about disabling/enabling write cache, i
> tried to test in on desktop 3.5" drive
>
> kern.cam.ada.write_cache: 1
> kern.cam.ada.read_ahead: 1
> kern.cam.ada.0.read_ahead: -1
> kern.cam.ada.0.write_cache: -1
>
> i tried writing 1 or 0 to kern.cam.ada.0.write_cache, and there were
> exactly no differences at all, and disk seems to do always write caching.
>
> Does that drive lie and ignore commands or i do it wrong?
>
> this is my disk.
>
> ada0 at ahcich0 bus 0 scbus0 target 0 lun 0
> ada0: <SAMSUNG HD501LJ CR100-10> ATA-8 SATA 2.x device
> ada0: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes)
> ada0: Command Queueing enabled
> ada0: 476940MB (976773168 512 byte sectors: 16H 63S/T 16383C)
>
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