WD AV drives not for desktop use
Ed Light
--
Ed Light
Better World News TV Channel:
http://realnews.com
Iraq Veterans Against the War and Related:
http://ivaw.org
http://couragetoresist.org
http://antiwar.com
Send spam to the FTC at
sp...@uce.gov
Thanks, robots.
Arno
> http://www.techarp.com/showarticle.aspx?artno=659&pgno=4
Fortunately these should be more expensive and not
show up in cheap computers. But some people will
recycle them and run into problems.
Arno
--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: ar...@wagner.name
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
Rod Speed
> Ed Light <nob...@nobody.there> wrote:
>> http://www.techarp.com/showarticle.aspx?artno=659&pgno=4
> Fortunately these should be more expensive
Not necessarily, it depends on how widespread
PVR use becomes compared with PCs etc.
> and not show up in cheap computers. But some
> people will recycle them and run into problems.
Thats always a potential with any recycling.
Ed Light
> Ed Light<nob...@nobody.there> wrote:
>> http://www.techarp.com/showarticle.aspx?artno=659&pgno=4
>
> Fortunately these should be more expensive and not
> show up in cheap computers. But some people will
> recycle them and run into problems.
>
> Arno
newegg has alot of them listed. The prices are comparable to other drives.
Arno
> On 6/28/2011 9:50 AM, Arno wrote:
>> Ed Light<nob...@nobody.there> wrote:
>>> http://www.techarp.com/showarticle.aspx?artno=659&pgno=4
>>
>> Fortunately these should be more expensive and not
>> show up in cheap computers. But some people will
>> recycle them and run into problems.
>>
>> Arno
> newegg has alot of them listed. The prices are comparable to other drives.
Hmm, not good. These are not general-purpose components. If
I read it right, they do not do any error correction.
Nuser
> http://www.techarp.com/showarticle.aspx?artno=659&pgno=4
A number of years ago I acquired 4x500GB Hitachi drives sold in the
sealed original packaging as part of a job lot, they were sold as
identical. However when I received the drives 2 of them were DeskStars,
1 was a faster version (which I forget the model name atm) and 1 was a
CinemaStar drive which is a similar AV-specific drive to the WD drives
mentioned in the link.
The only real difference in performance was the drive had a quicker
access times, better IO transaction rate but much slower (but *far* more
consistent) transfer rate than other drives. It is runs quieter, cooler
and sucks a little less power too (despite it still being a 7200rpm drive).
After talking to a guy who worked at Hitachi (but does no longer)he told
me that in fact these drives were *less* prone to errors when used in
normal systems, that in fact the full AV "mode" had to be enabled
specifically and the drives were shipped in a "hybrid" mode. This mode
was apparently not vendor specific so maybe the WD drives arent as bad
as this article makes out.
I wouldn't recommend them unless access time/IO rate is a priority and
definitely not if you are looking for high transfer rate, but otherwise
if you find them at a bargain price then don't shy away.
Mike Tomlinson
escribi�:
>Hmm, not good. These are not general-purpose components. If
>I read it right, they do not do any error correction.
Exactly. Or they do very minimal correction, favouring keeping up a
stream of data over data accuracy.
Such drives are sometimes also marked "CE" (consumer electronics), not
to be confused with the European CE symbol.
--
(\__/)
(='.'=)
(")_(")
Mike Tomlinson
<nu...@no.to.spam> escribi�:
>identical. However when I received the drives 2 of them were DeskStars,
>1 was a faster version (which I forget the model name atm)
Ultrastar. IBM/Hitachi's name for their enterprise range.
Franc Zabkar
finger to keyboard and composed:
>http://www.techarp.com/showarticle.aspx?artno=659&pgno=4
AFAICS, that author of that article is misinformed.
AIUI, the drive only skips over bad blocks when its Streaming Command
Set is enabled. The drive still supports the regular command set. In
fact, these commands *must* be used whenever the file system is
updated. The user of an AV-GP drive may not care about a dropped video
frame, but he must have confidence that his file system is intact.
Furthermore, a drive that supports TLER (Time Limited Error Recovery)
is to be preferred over non-TLER capable drives in RAID environments.
A drive that takes too long to recover from an error may drop out of a
RAID.
FWIW, here is an excerpt from a Seagate technology paper:
Seagate Briefing: Optimizing Surveillance DVR Reliability:
http://www.axetech.be/Pdf/Accessoires/HD/Seagate%20Technology%20Paper%20_SV35%20QandA.pdf
"Perhaps surprisingly, complete data integrity for video is not
vitally important. That�s because a small error introduced into a
video stream doesn�t compromise the overall integrity of the visual
image. While a small, perhaps imperceptible, flaw may occur, the
overall video is still intact. However, in order to manage the vast
amounts of video and related metadata in a surveillance system, a
keyed relational database or similar traditional data organizational
system is often used. It is absolutely critical that reads and writes
for such systems employ the utmost levels of error correction and
detection to ensure data integrity isn�t compromised.
An important feature of the SV35 Series disc drive is its support of
the ATA-7 streaming command set. ATA-7 is a recent extension of the
industry-standard ATA command set for controlling disc drives. The
streaming component of this standard enables the SV35 Series drive�s
reads and writes to be customized for either video or data payloads.
Using the ATA-7 streaming commands, both of these requirements are
elegantly met."
Section 4.3 of the following document lists the supported ATA commands
for Seagate's video surveillance models.
SV35 Series SATA Product Manual, Rev. D:
http://www.seagate.com/staticfiles/support/disc/manuals/ce/SV35%20Series/SV35.5%20Series/100562053d.pdf
These ATA commands include the following:
Read DMA (C8h)
Read DMA Without Retries (C9h)
Read Sectors (20h)
Read Sectors Without Retries (21h)
Read Verify Sectors (40h)
Read Verify Sectors Without Retries (41h)
Write DMA (CAh)
Write DMA Without Retries (CBh)
Write Sectors (30h)
Write Sectors Without Retries (31h)
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
Arno
> On Sun, 26 Jun 2011 22:59:57 -0700, Ed Light <nob...@nobody.there> put
> finger to keyboard and composed:
>>http://www.techarp.com/showarticle.aspx?artno=659&pgno=4
> AFAICS, that author of that article is misinformed.
> AIUI, the drive only skips over bad blocks when its Streaming Command
> Set is enabled. The drive still supports the regular command set. In
> fact, these commands *must* be used whenever the file system is
> updated. The user of an AV-GP drive may not care about a dropped video
> frame, but he must have confidence that his file system is intact.
Hmmm. Possible. Sounds even likely.
> Furthermore, a drive that supports TLER (Time Limited Error Recovery)
> is to be preferred over non-TLER capable drives in RAID environments.
> A drive that takes too long to recover from an error may drop out of a
> RAID.
Depends on teh RAID. With Linux Software RAID that is not a problem.
For some Hardware RAID cards with old firmware, it is. But basically
TLER is a scan to allow the manufactuers to ask more money for the
same drive with some minor firmware changes.
> FWIW, here is an excerpt from a Seagate technology paper:
> Seagate Briefing: Optimizing Surveillance DVR Reliability:
> http://www.axetech.be/Pdf/Accessoires/HD/Seagate%20Technology%20Paper%20_SV35%20QandA.pdf
> "Perhaps surprisingly, complete data integrity for video is not
> vitally important. That?s because a small error introduced into a
> video stream doesn?t compromise the overall integrity of the visual
> image. While a small, perhaps imperceptible, flaw may occur, the
> overall video is still intact. However, in order to manage the vast
> amounts of video and related metadata in a surveillance system, a
> keyed relational database or similar traditional data organizational
> system is often used. It is absolutely critical that reads and writes
> for such systems employ the utmost levels of error correction and
> detection to ensure data integrity isn?t compromised.
> An important feature of the SV35 Series disc drive is its support of
> the ATA-7 streaming command set. ATA-7 is a recent extension of the
> industry-standard ATA command set for controlling disc drives. The
> streaming component of this standard enables the SV35 Series drive?s
> reads and writes to be customized for either video or data payloads.
> Using the ATA-7 streaming commands, both of these requirements are
> elegantly met."
> Section 4.3 of the following document lists the supported ATA commands
> for Seagate's video surveillance models.
> SV35 Series SATA Product Manual, Rev. D:
> http://www.seagate.com/staticfiles/support/disc/manuals/ce/SV35%20Series/SV35.5%20Series/100562053d.pdf
> These ATA commands include the following:
> Read DMA (C8h)
> Read DMA Without Retries (C9h)
> Read Sectors (20h)
> Read Sectors Without Retries (21h)
> Read Verify Sectors (40h)
> Read Verify Sectors Without Retries (41h)
> Write DMA (CAh)
> Write DMA Without Retries (CBh)
> Write Sectors (30h)
> Write Sectors Without Retries (31h)
Ok, so these AV drives are _not_ a problem in normal operation.
Ed Light
PC data, so we'll see what they say.
Ed Light
"The AV drives are designed to be used on Audio/Video equipment but
using it on a computer would not create any problems. We know that it is
save to use our AV drives with computers and no error would occur."
Yousuf Khan
> En el artículo<96ur0u...@mid.individual.net>, Arno<m...@privacy.net>
> escribió:
>
>> Hmm, not good. These are not general-purpose components. If
>> I read it right, they do not do any error correction.
>
> Exactly. Or they do very minimal correction, favouring keeping up a
> stream of data over data accuracy.
>
> Such drives are sometimes also marked "CE" (consumer electronics), not
> to be confused with the European CE symbol.
I don't think so, you would need to enable certain special modes of this
drive to skip error correction like that. I would assume that they come
configured like standard drives out of the box, and only go into these
special modes, when they are attached to some sort of PVR.
Then that brings up the question, how many PVR's actually can make use
of this special mode? I would guess not many of them are aware of this
feature.
Yousuf Khan
Mike Tomlinson
<bbb...@spammenot.yahoo.com> escribió:
>I don't think so, you would need to enable certain special modes of this
>drive to skip error correction like that.
Perhaps, then, you could explain the CE-marked Western Digital drive I
have in my PVR?
http://forums.digitalspy.co.uk/showthread.php?p=13294509
http://www.seagate.com/www/en-us/products/consumer_electronics/
http://www.astra2d.com/sky+2.html
"Better streaming video performance - ensuring that you always get a
great picture. CE drives are optimized for streaming to avoid the
stutters and jerkiness that can be caused by repeated error checking
that occurs on regular desktop PC drives. Hard disk drives designed for
PC applications are optimized for data integrity through enhanced error
detection and correction routines. These error correction 'features' on
PC drives cause the data flow to be paused until an error is corrected,
which causes jerky playback of video and audio."
> I would assume that they come
>configured like standard drives out of the box, and only go into these
>special modes, when they are attached to some sort of PVR.
No, they're supplied already configured in those "special modes", which
is why they should not be used in desktop PCs.
>Then that brings up the question, how many PVR's actually can make use
>of this special mode?
They don't need to. The drive does it.
Arno
> From Western Digital:
> "The AV drives are designed to be used on Audio/Video equipment but
> using it on a computer would not create any problems. We know that it is
> save to use our AV drives with computers and no error would occur."
Good to know. So this is a commend extension only and if you do not
use the "no retry" commands, no prolems arise.
Thanks for investigating and posting this!
Yousuf Khan
>> I would assume that they come
>> configured like standard drives out of the box, and only go into these
>> special modes, when they are attached to some sort of PVR.
>
> No, they're supplied already configured in those "special modes", which
> is why they should not be used in desktop PCs.
>
>> Then that brings up the question, how many PVR's actually can make use
>> of this special mode?
>
> They don't need to. The drive does it.
No, Frank Z. explained it here, there is no special streaming mode, but
there are special streaming versions of the ATA commandset. Standard ATA
commands like "Read DMA" would have an complementary streaming command
like "Read DMA without retries". A PC running the same drives would only
ever use the retriable commands, whereas a PVR would use the
non-retriable commands.
Yousuf Khan
Ed Light
> Thanks for investigating and posting this!
Thanks for sharing your experience!
Yousuf Khan
> From Western Digital:
>
> "The AV drives are designed to be used on Audio/Video equipment but
> using it on a computer would not create any problems. We know that it is
> save to use our AV drives with computers and no error would occur."
Now, I wonder if a Cisco 8642HD PVR would be able to make use of this
special streaming commandset? I wouldn't want to go buy one of these and
find out that it's simply being used as a normal drive with the standard
commandset.
Yousuf Khan
John Turco
>
> En el art�culo <4e0d4c5c$1...@news.bnb-lp.com>, Yousuf
> Khan <bbb...@spammenot.yahoo.com> escribi�:
<deleted entire message, for brevity>
Hold on, amigo! What's all this "En el art�culo" and
"escribi�" stuff about, anyway?
Your e-mail address ends in "uk" -- so, Miguel, it's
logical to assume you're in Britain, not Spain.
--
Cordially,
John Turco <jt...@concentric.net>
Marie's Musings <http://fairiesandtails.blogspot.com>
Mike Tomlinson
<jt...@concentric.net> escribió:
>Your e-mail address ends in "uk" -- so, Miguel, it's
>logical to assume you're in Britain, not Spain.
El español es el idioma más hablado del planeta, Juan. :o)
Ed Light
> Your e-mail address ends in "uk" -- so, Miguel, it's
> logical to assume you're in Britain, not Spain.
Blessedly, Spanish speakers are all over the planet.
Tom Del Rosso
Arno wrote:
> Ed Light <nob...@nobody.there> wrote:
> > http://www.techarp.com/showarticle.aspx?artno=659&pgno=4
>
> Fortunately these should be more expensive and not
> show up in cheap computers. But some people will
> recycle them and run into problems.
A mpeg file can be copied over 100 times faster than it takes to play it.
The disk's speed therefore seems to be so much faster than needed for video,
why is it even necessary to speed it up by reducing the error-correction?
--
Reply in group, but if emailing add one more
zero, and remove the last word.
Mike Tomlinson
<td...@verizon.net.invalid> escribió:
>A mpeg file can be copied over 100 times faster than it takes to play it.
>The disk's speed therefore seems to be so much faster than needed for video,
>why is it even necessary to speed it up by reducing the error-correction?
Because PVRs don't just play; they simultaneously record, from two
sources on twin-tuner models, and have features such as live pause and
action replay. So the disk may be having to deal with simultaneous
multiple streams of data.
Rod Speed
> Arno wrote
>> Ed Light <nob...@nobody.there> wrote
>>> http://www.techarp.com/showarticle.aspx?artno=659&pgno=4
>> Fortunately these should be more expensive and not
>> show up in cheap computers. But some people will
>> recycle them and run into problems.
> A mpeg file can be copied over 100 times faster than it takes to play it. The disk's speed therefore seems to be so
> much faster than needed for video, why is it even necessary to speed it up by reducing the error-correction?
Because the worst of the retrys on error correction with writes can see
a significant glitch in the video file. When the error correction isnt as
aggressive, the glitch is much less noticeable.
Rod Speed
> John Turco wrote
>> Your e-mail address ends in "uk" -- so, Miguel, it's logical to assume you're in Britain, not Spain.
> Blessedly, Spanish speakers are all over the planet.
There are a hell of a lot more english speakers.
Tom Del Rosso
That's only 3 or 4 times the load, but I can see that thrashing and
re-seeking would slow it down a lot more.
Constant thrashing for long periods causes wear and heating too, so I wonder
if they are designed for that.
John Turco
>
> > En el artículo <4E17CF0A...@concentric.net>, John
> > Turco <jt...@concentric.net> escribió:
> >
> > Your e-mail address ends in "uk" -- so, Miguel, it's
> > logical to assume you're in Britain, not Spain.
>
> El español es el idioma más hablado del planeta, Juan. :o)
!No comprende!
Or, I'll take a stab at an English translation:
"Spanish is the language spoken in more of the world,
John."
("More" is accurate..."most" isn't.)
turne...@yahoo.co.uk
116...@gmail.com
>
> Fortunately these should be more expensive and not
> show up in cheap computers. But some people will
> recycle them and run into problems.
>
But I always check the SMART data first. Some had a disturbing maximum temperature
(up to 80 Celcius). Perhaps somebody left the TV magazine on top, blocking the
vents.