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Date:      Mon, 26 Mar 2007 21:21:34 +0200
From:      =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@deepcore.dk>
To:        Mikhail Teterin <mi+kde@aldan.algebra.com>
Cc:        Dmitry Pryanishnikov <dmitry@atlantis.dp.ua>, stable@freebsd.org, Derek Ragona <derek@computinginnovations.com>, Brian Candler <B.Candler@pobox.com>
Subject:   Re: pitiful performance of an SATA150 drive
Message-ID:  <46081D3E.5070204@deepcore.dk>
In-Reply-To: <200703261436.28659@aldan>
References:  <200603010505.k2155HfQ003205@aldan.algebra.com> <44054C5E.5070902@deepcore.dk> <200603011107.09942@aldan> <200703261436.28659@aldan>

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Mikhail Teterin wrote:
> Over a year later this remains a problem -- exactly as described below.=
=2E.
>
> No other SATA devices are present -- the only other IDE device is the D=
VD=20
> drive. My main disks are SCSI.
>
> What's MUCH worse is that the (slowly) written data is also often corru=
pted...=20
> I use the drive to store our vast collection of photos and the backups.=
 Every=20
> once in a while I encounter a corrupt JPEG file, and the backups are _a=
lways_=20
> corrupt somewhere. Doing something like:
>
> 	dump 0auChf 16 0 - /home | bzip2 -9 > /store/home.0.bz2
>
> always produces a corrupt file (as per ``bzip2 -t''). I used to blame t=
he=20
> drive's temperature, but it now sits in its own enclosure and stays und=
er 40=20
> Celsius.
>
> When the drive is accessed, there are (according to `systat -vm') many =

> thousands of interrupts 17 -- on my system these are shared between pcm=
0 and=20
> ehci0. Why are these triggered by accessing SATA is unclear, but the In=
tr's=20
> share of the CPU time is often above 80% of one processor's total (I ha=
ve 4=20
> processors).
>
> As I mentioned a year ago, Knoppix was accessing the same drive at much=
 higher=20
> speeds, so I don't believe, the problem is with the hardware...
>  =20
What HW was this again, there has been alot of updates/changes over the=20
last year ?
Could you try an up to date -current kernel on this, at least to get me=20
a decent dmesg from ?
If thats impossible take ATA from current modulus the busdma changes and =

use that on an up to date 6-stable.
I cant tell what interrupts go where without a dmesg...

Other than that, single bit/byte corruption are normally HW troubles of=20
some kind, usually involving bad/incompatible memory or bad chipsets.
However, if your drive has been overheated the media might have taken=20
permanent damage that makes it loose data.
What does SMART say on corrected errors etc (if the drive has that info).=


-S=F8ren
> Please, advise. Thanks!
>
> 	-mi
>
> On Wednesday 01 March 2006 11:07, Mikhail Teterin wrote:
> =3D On Wednesday 01 March 2006, S=F8ren Schmidt wrote:
> =3D =3D dd if=3D/dev/ad8 of=3D/dev/null bs=3D1m
> =3D=20
> =3D Well, as I said, there is no obvious problems with _reading_. The a=
bove=20
> =3D command reads at well over 60Mb/s:
> =3D=20
> =3D 	1638924288 bytes transferred in 25.374856 secs (64588516 bytes/sec=
)
> =3D=20
> =3D _Writing_, however, remains pathetic:
> =3D=20
> =3D 	dd of=3D/dev/ad8 if=3D/dev/zero bs=3D1m
> =3D 	631242752 bytes transferred in 91.039066 secs (6933757 bytes/sec)
> =3D=20
> =3D =3D The problem is the blocksize that gets in the way of utilizing =
full
> =3D =3D transfer speed.
> =3D=20
> =3D Did you really expect the blocksize to make an order of (decimal) m=
agnitude=20
> =3D difference? :-) It made no difference at all :-(
> =3D=20
> =3D Brian Candler asked:
> =3D =3D Just to be clear: this is Knoppix running on the *same* machine=
 as you've
> =3D =3D been testing FreeBSD?
> =3D=20
> =3D Correct.
> =3D=20
> =3D =3D Aside: why are you using cat under FreeBSD, but dd under Knoppi=
x? I'd use=20
> dd
> =3D =3D everywhere for consistency.
> =3D=20
> =3D Cat was slightly faster in my tests on FreeBSD. I used dd under Kno=
ppix for=20
> =3D dd's throughput reporting -- I'm not aware of a monitoring tool lik=
e=20
> `systat'=20
> =3D under Linux.
> =3D=20
> =3D Yours,
> =3D=20
> =3D 	-mi
> =3D=20
>
> .
>
>  =20





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