SATA1 and SATA2 data rate

NTFSD
1

I’m developing a filter driver that needs to do some data processing over
the incoming/outgoing stream and I’m a bit puzzled about the rates I need to
support.
SATA1 data rate is 150MB/s and SATA2 is 300MB/s, however those rates are
peak rates that could probably be reached only when having full cache
utilization.
I assume that in average, the rate I need to support is much lesser.
Any idea what is the steady state rate I need to support for SATA1 and for
SATA2 (assuming only one HD is connected and no RAID present)?

2

~80 MB/s. Newest SCSI will do 140 MB/s. If you are doing processing of
sequentially read/written data, these rates are pretty much constant, i.e. will only
drop a bit at the end of the drive.

Yoram Shacham wrote:

I’m developing a filter driver that needs to do some data processing over
the incoming/outgoing stream and I’m a bit puzzled about the rates I need to
support.
SATA1 data rate is 150MB/s and SATA2 is 300MB/s, however those rates are
peak rates that could probably be reached only when having full cache
utilization.
I assume that in average, the rate I need to support is much lesser.
Any idea what is the steady state rate I need to support for SATA1 and for
SATA2 (assuming only one HD is connected and no RAID present)?

Questions? First check the IFS FAQ at https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: xxxxx@alfasp.com
To unsubscribe send a blank email to xxxxx@lists.osr.com

–
King regards, Dejan
http://www.alfasp.com
File system audit, security and encryption kits.

3

P.S. the ~80MB/s rates are for both SATA 1 and SATA 2 drives.

Yoram Shacham wrote:

I’m developing a filter driver that needs to do some data processing over
the incoming/outgoing stream and I’m a bit puzzled about the rates I need to
support.
SATA1 data rate is 150MB/s and SATA2 is 300MB/s, however those rates are
peak rates that could probably be reached only when having full cache
utilization.
I assume that in average, the rate I need to support is much lesser.
Any idea what is the steady state rate I need to support for SATA1 and for
SATA2 (assuming only one HD is connected and no RAID present)?

Questions? First check the IFS FAQ at https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: xxxxx@alfasp.com
To unsubscribe send a blank email to xxxxx@lists.osr.com

–
King regards, Dejan
http://www.alfasp.com
File system audit, security and encryption kits.

4

How come the SCSI is much faster at the steady state?
Isn’t the steady state speed dictated by the physical disk components and
not by the data interface?

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Dejan Maksimovic

~80 MB/s. Newest SCSI will do 140 MB/s. If you are doing processing of
sequentially read/written data, these rates are pretty much constant, i.e.
will only
drop a bit at the end of the drive.

I’m developing a filter driver that needs to do some data processing over
the incoming/outgoing stream and I’m a bit puzzled about the rates I need
to
support.
SATA1 data rate is 150MB/s and SATA2 is 300MB/s, however those rates are
peak rates that could probably be reached only when having full cache
utilization.
I assume that in average, the rate I need to support is much lesser.
Any idea what is the steady state rate I need to support for SATA1 and for
SATA2 (assuming only one HD is connected and no RAID present)?

5

In general these days high-end SCSI drives have 15000 RPMs and 2.5" plates
and SATA drives are just 7200 RPMs and 3.5". SCSI drives have 1.5x higher
linear media speed.

Dmitriy Budko
VMware

-----Original Message-----
From: xxxxx@lists.osr.com [mailto:bounce-264028-
xxxxx@lists.osr.com] On Behalf Of Yoram Shacham
Sent: Wednesday, September 27, 2006 3:48 PM
To: Windows File Systems Devs Interest List
Subject: RE: [ntfsd] SATA1 and SATA2 data rate

How come the SCSI is much faster at the steady state?
Isn’t the steady state speed dictated by the physical disk components and
not by the data interface?

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Dejan Maksimovic

~80 MB/s. Newest SCSI will do 140 MB/s. If you are doing processing of
sequentially read/written data, these rates are pretty much constant, i.e.
will only
drop a bit at the end of the drive.

6

Currently there are a few SCSI disks that will sustain ~100 MB/s, but only one
that will do 140MB/s (that rate diminishes as we near the end of the drive of course,
as with any drive). It is not dictated by the interface.
The SCSI I am referring to that can do 140MB/s are the Seagate’s 15K.5 drives.
The perpendicular recording adds to performance quite nice due to added density, but
the 15K RPM also plays a role here, as the SATA version cannot reach 90MB/s even. On
a side note, I have not seen any drive whose speed diminishes as fast as 15K.5’s.
Though it goes down to ~80MB/s which is more than many drives start with, the almost
50% slower rate is not trivial.

Deja.

Yoram Shacham wrote:

How come the SCSI is much faster at the steady state?
Isn’t the steady state speed dictated by the physical disk components and
not by the data interface?

–
King regards, Dejan
http://www.alfasp.com
File system audit, security and encryption kits.