SATA 2 HD with very fast sustained transfer rate

The company at which I am working have finally decided that they need to
log data from their equipment, which has an interface that is mechanically
compatible with SATA, and could implement a 3Gb/s SATA 2 interface.

Reading the Seagate Barracuda 7200.11 datasheet at
http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_11.pdf I
note that the "Sustained Data Rate OD" is between 105MB/s and 120MB/s,
depending on precise model. We need at least 90MB/s per data channel... Is
that likely to be about the best acheivable for SATA 2? Or can you suggest
a faster SATA 2 disk drive family?

Thanks in advance!
	   
					
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"RCIngham" <robert.ingham@n_o_s_p_a_m.gmail.com> writes:
>Reading the Seagate Barracuda 7200.11 datasheet at
>http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_11.pdf I
>note that the "Sustained Data Rate OD" is between 105MB/s and 120MB/s,
>depending on precise model. We need at least 90MB/s per data channel... Is
>that likely to be about the best acheivable for SATA 2? Or can you suggest
>a faster SATA 2 disk drive family?

Thats typical for most, and your 90MB/s would be too close for my
comfort zone for sustained transfer rates required. 

How about SSD disks? They go much faster, at least double. 

Otherwise, I'd recommend a RAID of disks, although for embedded
situations, SSD would probably work better. 

RCIngham wrote:

> The company at which I am working have finally decided that they need to
> log data from their equipment, which has an interface that is mechanically
> compatible with SATA, and could implement a 3Gb/s SATA 2 interface.
> 
> Reading the Seagate Barracuda 7200.11 datasheet at
> http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_11.pdf I
> note that the "Sustained Data Rate OD" is between 105MB/s and 120MB/s,
> depending on precise model. We need at least 90MB/s per data channel... Is
> that likely to be about the best acheivable for SATA 2? Or can you suggest
> a faster SATA 2 disk drive family?

Keep in mind that the OS and the system overhead is likely to reduce the 
  HDD raw transfer rate to a half or so.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

>
>RCIngham wrote:
>
>> The company at which I am working have finally decided that they need
to
>> log data from their equipment, which has an interface that is
mechanically
>> compatible with SATA, and could implement a 3Gb/s SATA 2 interface.
>> 
>> Reading the Seagate Barracuda 7200.11 datasheet at
>> http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_11.pdf
I
>> note that the "Sustained Data Rate OD" is between 105MB/s and 120MB/s,
>> depending on precise model. We need at least 90MB/s per data channel...
Is
>> that likely to be about the best acheivable for SATA 2? Or can you
suggest
>> a faster SATA 2 disk drive family?
>
>Keep in mind that the OS and the system overhead is likely to reduce the 
>  HDD raw transfer rate to a half or so.
>
>
>Vladimir Vassilevsky
>DSP and Mixed Signal Design Consultant
>http://www.abvolt.com
>
No OS here! There might have to be software to manage the Link Layer stuff,
but that could be on a dedicated (soft) processor...
	   
					
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On 7/11/2011 8:56 AM, RCIngham wrote:
> The company at which I am working have finally decided that they need to
> log data from their equipment, which has an interface that is mechanically
> compatible with SATA, and could implement a 3Gb/s SATA 2 interface.
>
> Reading the Seagate Barracuda 7200.11 datasheet at
> http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_11.pdf I
> note that the "Sustained Data Rate OD" is between 105MB/s and 120MB/s,
> depending on precise model. We need at least 90MB/s per data channel... Is
> that likely to be about the best acheivable for SATA 2? Or can you suggest
> a faster SATA 2 disk drive family?

Do you need "90MB/s" *continuously* (sustained indefinitely)?

Keep in mind that you still have to be able to *move* 90MB/s through
your filesystem stack (i.e., make sure your OS-I/O can actually do
what you need).

And, recall the drive will also do periodic thermal recalibrations
which will reduce the drive's "availability", temporarily.

RCIngham wrote:
>The company at which I am working have finally decided that they need to
>log data from their equipment, which has an interface that is mechanically
>compatible with SATA, and could implement a 3Gb/s SATA 2 interface.
>
>Reading the Seagate Barracuda 7200.11 datasheet at
>http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_11.pdf I
>note that the "Sustained Data Rate OD" is between 105MB/s and 120MB/s,
>depending on precise model. We need at least 90MB/s per data channel... Is
>that likely to be about the best acheivable for SATA 2? Or can you suggest
>a faster SATA 2 disk drive family?

As others already mentioned, RAID systems can easily reach transfer
rates of several hundred megabytes/sec using commercial level disks.

For a recent example, I just installed Solaris 11 on an HP Proliant
Microserver.  Simple tests using dd and files of 1Gb and 2Gb produced
more than 200Mb/sec on an redundant (raidz2) disk pool, and close to
400 Mb/sec on a stripped disk pool. All this with an AMD low power
processor (just above Intel's Atom,) and using "green" 5900 RPM disks.
(5 drives)

Other options:

10K/15K SCSI disks, (expensive, lower capacity)
fiberchannel, (expensive)
SSD - (very expensive)

You can buy external enclosures that would "strip" a group of disks.
without the need to configure an external OS, drivers, etc.
They came with eSATA, fiberchannel or iSCSI (ethernet) interfaces.
(eSATA may require disk multiplexing support from your SATA interface)

If you have (or can add) a fast network interface, iSCSI may be a good
approach..

For RAID based solutions, the bottleneck is more likely to be on how
to transfer the data to the disk array system, not to the disks
themselves. 

Try asking in a file server or data base server forum. Those guys need
to solve this type of problem every day.
--
Roberto Waltman

[ Please reply to the group.
  Return address is invalid ]

Roberto Waltman wrote:
>...
>Other options:
>
>10K/15K SCSI disks, (expensive, lower capacity)
>fiberchannel, (expensive)
>SSD - (very expensive)

For example, (anything but SATA)
http://www.seagate.com/www/en-us/products/enterprise-hard-drives/cheetah-15k

--
Roberto Waltman

[ Please reply to the group.
  Return address is invalid ]

>On 7/11/2011 8:56 AM, RCIngham wrote:
>> The company at which I am working have finally decided that they need
to
>> log data from their equipment, which has an interface that is
mechanically
>> compatible with SATA, and could implement a 3Gb/s SATA 2 interface.
>>
>> Reading the Seagate Barracuda 7200.11 datasheet at
>> http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_11.pdf
I
>> note that the "Sustained Data Rate OD" is between 105MB/s and 120MB/s,
>> depending on precise model. We need at least 90MB/s per data channel...
Is
>> that likely to be about the best acheivable for SATA 2? Or can you
suggest
>> a faster SATA 2 disk drive family?
>
>Do you need "90MB/s" *continuously* (sustained indefinitely)?

Yes. That is the per-channel raw data rate.

>Keep in mind that you still have to be able to *move* 90MB/s through
>your filesystem stack (i.e., make sure your OS-I/O can actually do
>what you need).

As mentioned previously, no OS.

>And, recall the drive will also do periodic thermal recalibrations
>which will reduce the drive's "availability", temporarily.

Not good. Unless I can turn them off during capture sessions.
	   
					
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On 7/11/2011 2:41 PM, RCIngham wrote:
>> On 7/11/2011 8:56 AM, RCIngham wrote:

>> Do you need "90MB/s" *continuously* (sustained indefinitely)?
>
> Yes. That is the per-channel raw data rate.

Yes, but (below) you mention "capture sessions" -- suggesting
there are "non-capture sessions" as well.  So, the question
then becomes, how long (in terms of data) are these sessions?

>> Keep in mind that you still have to be able to *move* 90MB/s through
>> your filesystem stack (i.e., make sure your OS-I/O can actually do
>> what you need).
>
> As mentioned previously, no OS.

OK.  But you'll still need a mechanism to move bytes from the
application layer down through to the I/O subsystem.

>> And, recall the drive will also do periodic thermal recalibrations
>> which will reduce the drive's "availability", temporarily.
>
> Not good. Unless I can turn them off during capture sessions.

A/V drives don't run these calibration cycles (or at least not
as *often*).

You may be able to "ride one out" if you have enough buffering in the
host (plus the drive itself).  You'd have to look at the specifics
of each drive (I've never had to deal with that aspect).