SATA II RAID 0 not reaching 3.0 Gbps

On or about Sat, 28 Jun 2008 17:57:13 +0800 did "Man-wai Chang ToDie (33.6k)"
dribble thusly:


Chipset is nForce 570 Ultra.

Whatever possessed you to think it would? 3.0Gbps indicates the maximum
interface transfer rate for a single drive (which no current SATA drive can
meet, much less exceed). It has nothing to do with the speed of an array of
drives, each of which has their own connection (it's not like parallel SCSI).

At most, you can expect performance of P*N, where P is the performance of one
drive, and N is the number of drives.

Previously Mike Ruskai wrote:
On or about Sat, 28 Jun 2008 17:57:13 +0800 did "Man-wai Chang ToDie (33.6k)"
dribble thusly:


Chipset is nForce 570 Ultra.

Whatever possessed you to think it would? 3.0Gbps indicates the maximum
interface transfer rate for a single drive (which no current SATA drive can
meet, much less exceed). It has nothing to do with the speed of an array of
drives, each of which has their own connection (it's not like parallel SCSI).

At most, you can expect performance of P*N, where P is the performance of one
drive, and N is the number of drives.

Indeed. Another one that looked at the highest number and though
that it could be reached. The interface is allways faster than the
disk, in order for it to not be a bottleneck. Current disks can
reach something like 1Gbps maximum and typically slow down to
around half that at the end of the disk. RAID0 is not necessarily
that much faster.

Arno

Whatever possessed you to think it would? 3.0Gbps indicates the maximum
interface transfer rate for a single drive (which no current SATA drive can
meet, much less exceed). It has nothing to do with the speed of an array of
drives, each of which has their own connection (it's not like parallel SCSI).
Indeed. Another one that looked at the highest number and though
that it could be reached. The interface is allways faster than the
disk, in order for it to not be a bottleneck. Current disks can
reach something like 1Gbps maximum and typically slow down to
around half that at the end of the disk. RAID0 is not necessarily
that much faster.

Is there a way/program that measures the speed of data transfer in the
SATA cables? HDTune doesn't seem to do it as the interface of my PC was
SATA II.

--
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Man-wai Chang ToDie (33.6k) wrote:

Is there a way/program that measures the speed of data transfer in the
SATA cables? HDTune doesn't seem to do it as the interface of my PC was
SATA II.
HDTach free version.

---
Ed Light

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Thanks, robots.

Is there a way/program that measures the speed of data transfer in the
SATA cables? HDTune doesn't seem to do it as the interface of my PC
was SATA II.
HDTach free version.

It really does?

--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
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Man-wai Chang ToDie (33.6k) wrote:
Is there a way/program that measures the speed of data transfer in
the SATA cables? HDTune doesn't seem to do it as the interface of my
PC was SATA II.
HDTach free version.

It really does?


Yes, it calls it the "Burst Speed".

---
Ed Light

Better World News TV Channel:
http://realnews.com

Bring the Troops Home:
http://bringthemhomenow.org
http://antiwar.com

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http://couragetoresist.org

Send spam to the FTC at

Thanks, robots.

HDTach free version.
It really does?
Yes, it calls it the "Burst Speed".

Do you happen to know why HDTune doesn't report 3Gbps burst speed?
HDTach really reported burst speed of 3Gbps....

--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
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Man-wai Chang ToDie (33.6k) wrote:
HDTach free version.
It really does?
Yes, it calls it the "Burst Speed".

Do you happen to know why HDTune doesn't report 3Gbps burst speed?
HDTach really reported burst speed of 3Gbps....


I haven't used HDTune.
---
Ed Light

Better World News TV Channel:
http://realnews.com

Bring the Troops Home:
http://bringthemhomenow.org
http://antiwar.com

Iraq Veterans Against the War:
http://ivaw.org
http://couragetoresist.org

Send spam to the FTC at

Thanks, robots.

Man-wai Chang ToDie (33.6k) wrote:
HDTach free version.

It really does?

Yes, it calls it the "Burst Speed".


Do you happen to know why HDTune doesn't report 3Gbps burst speed?
HDTach really reported burst speed of 3Gbps....


HDtach and HDtune both report read burst speed, which should be the speed
*measured* when copying data from the HD's cache into the PC's main
memory. For the measured burst speed to be equal to the SATA link
peak speed (150/300 MB/s for SATA-I/II), every component in the chain
between the HD's cache and the PC's main memory must be at least as
fast as the SATA link, including the data mover engine between the
HD's cache and the SATA, and the data mover engine(s) between the SATA
link and the PC's main memory.

HDtach and HDtune do not always agree on read burst speed. For example,
the WD740 on this P4 with a SATA-I link is reported by HDtach as 119.4 MB/s
read burst, while HDtune shows 101.9 MB/s. Since HDtach's reported data
agrees with Storage Review and with WDC's (vendor) site, you can easily
guess whether I believe HDtach or HDtune.
--
Cheers, Bob

HDtach and HDtune do not always agree on read burst speed. For example,
the WD740 on this P4 with a SATA-I link is reported by HDtach as 119.4 MB/s
read burst, while HDtune shows 101.9 MB/s. Since HDtach's reported data
agrees with Storage Review and with WDC's (vendor) site, you can easily
guess whether I believe HDtach or HDtune.

Thanks.

--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
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