freemont wrote:
> I'm currently transferring about two hundred gigabytes of data from one
> drive in my computer to another.
>
> Why is it that with two 3 Gbit/s, 7200 SATA drives, moving data from one
> to the other maxes out around 45 MiB/s?
>
> This machine has an Intel E8400 processor and 4G RAM. I would expect
> transfers between drives to fly. Is this the sort of speed I should
> expect?
>

45MB/s is about right. Drive read/write speed is a lot slower than SATA
II bandwidth.

Check out the hard drive test charts on Tom's Hardware web site. Its an
eye opener.

on Monday 10 November 2008 15:48
in the Usenet newsgroup alt.os.linux.mandriva
Peaceful Bill wrote:

> freemont wrote:
>> I'm currently transferring about two hundred gigabytes of data from one
>> drive in my computer to another.
>>
>> Why is it that with two 3 Gbit/s, 7200 SATA drives, moving data from one
>> to the other maxes out around 45 MiB/s?
>>
>> This machine has an Intel E8400 processor and 4G RAM. I would expect
>> transfers between drives to fly. Is this the sort of speed I should
>> expect?
>>
>
> 45MB/s is about right. Drive read/write speed is a lot slower than SATA
> II bandwidth.
>
> Check out the hard drive test charts on Tom's Hardware web site. Its an
> eye opener.

You can measure your drive's performance with "hdparm -tT /dev/xxx".
Replace "xxx" with "sda", "hdb", or whatever.


--
sig goes here...
Peter D.

freemont wrote:

> I'm currently transferring about two hundred gigabytes of data from one
> drive in my computer to another.
>
> Why is it that with two 3 Gbit/s, 7200 SATA drives, moving data from one
> to the other maxes out around 45 MiB/s?
>
The 3GBit are only interface speed - you may get it for transferring from or
to the harddrive cache, but certainly not for a large transfer.

> This machine has an Intel E8400 processor and 4G RAM. I would expect
> transfers between drives to fly. Is this the sort of speed I should
> expect?
>
The real speed depends upon data density and speed of the platter, and count
of platters in a drive. That's why there are still 15kRpm drives, but you
don't want them for a desktop.

freemont wrote:
> I'm currently transferring about two hundred gigabytes of data from one
> drive in my computer to another.
>
> Why is it that with two 3 Gbit/s, 7200 SATA drives, moving data from one
> to the other maxes out around 45 MiB/s?
>
> This machine has an Intel E8400 processor and 4G RAM. I would expect
> transfers between drives to fly. Is this the sort of speed I should
> expect?

Bear in mind that Linux normally ships with DMA disabled, due to
problems on a few old pieces of hardware.

Check hard drive capabilities with hdparm -I /dev/sda
or whatever your device is, as root.

man hdparm
for more into.

Cheers!

jim b.


--
UNIX is not user unfriendly; it merely
expects users to be computer-friendly.

Jim Beard wrote:
> freemont wrote:
>> I'm currently transferring about two hundred gigabytes of data from
>> one drive in my computer to another.
>>
>> Why is it that with two 3 Gbit/s, 7200 SATA drives, moving data from
>> one to the other maxes out around 45 MiB/s?
>>
>> This machine has an Intel E8400 processor and 4G RAM. I would expect
>> transfers between drives to fly. Is this the sort of speed I should
>> expect?
>
> Bear in mind that Linux normally ships with DMA disabled, due to
> problems on a few old pieces of hardware.
>
> Check hard drive capabilities with hdparm -I /dev/sda
> or whatever your device is, as root.
>
> man hdparm
> for more into.
>
> Cheers!
>
> jim b.
>
>


Not at all. Unless both the drives are relatively new, 45Mbs is about
right.

On Mon, 10 Nov 2008 20:21:40 -0500, Jim Beard writ:

> freemont wrote:

>> Why is it that with two 3 Gbit/s, 7200 SATA drives, moving data from
>> one to the other maxes out around 45 MiB/s?

> Bear in mind that Linux normally ships with DMA disabled, due to
> problems on a few old pieces of hardware.
>
> Check hard drive capabilities with hdparm -I /dev/sda or whatever your
> device is, as root.
>
> man hdparm
> for more into.

I tried to enable 32-bit support on one of the drives, but it didn't take.
Is it because hdparm is for IDE drives? Should I be looking at sdparm
instead (not currently installed)?

[paul@lpt-20081029 nzb]$ sudo hdparm /dev/sda

/dev/sda:
IO_support = 0 (default)
readonly = 0 (off)
readahead = 256 (on)
geometry = 60801/255/63, sectors = 976773168, start = 0


[paul@lpt-20081029 nzb]$ sudo hdparm -Tt /dev/sda

/dev/sda:
Timing cached reads: 13344 MB in 1.99 seconds = 6703.77 MB/sec
Timing buffered disk reads: 276 MB in 3.02 seconds = 91.44 MB/sec

[paul@lpt-20081029 nzb]$ sudo hdparm -c1 /dev/sda

/dev/sda:
setting 32-bit IO_support flag to 1
HDIO_SET_32BIT failed: Invalid argument
IO_support = 0 (default)


--
"Because all you of Earth are idiots!"
¯`·.¸¸.·´¯`·-> freemont© <-·´¯`·.¸¸.·´¯

On Tue, 11 Nov 2008 02:41:27 +0000, freemont wrote:

> On Mon, 10 Nov 2008 20:21:40 -0500, Jim Beard writ:
>
>> freemont wrote:
>
>>> Why is it that with two 3 Gbit/s, 7200 SATA drives, moving data from
>>> one to the other maxes out around 45 MiB/s?

The transfer rate stated is the maximum (peak) rate that the drive can
reach. Sustained rates will depend on the bus and possibly on the memory
management.

>> Bear in mind that Linux normally ships with DMA disabled, due to
>> problems on a few old pieces of hardware.

Nearly all modern Linux distros ship with DMA enabled, and allow the user
to turn it off at boot with the ide=nodma boot parameter.

>> Check hard drive capabilities with hdparm -I /dev/sda or whatever your
>> device is, as root.
>>
>> man hdparm
>> for more into.
>
> I tried to enable 32-bit support on one of the drives, but it didn't
> take. Is it because hdparm is for IDE drives? Should I be looking at
> sdparm instead (not currently installed)?

Yes, you need sdparm to set parameters on SATA drives.