SATA problems

[Jeffrey Ross]

John Wendel wrote:
> Rohan Kulkarni wrote:
>>
>>
>> On 7/3/07, *Rohan Kulkarni* <rohan.ak1 at gmail.com 
>> <mailto:rohan.ak1 at gmail.com>> wrote:
>>
>>
>>
>>     On 7/2/07, *John Wendel* < john.wendel at metnet.navy.mil
>>     <mailto:john.wendel at metnet.navy.mil>> wrote:
>>
>>         Rohan Kulkarni wrote:
>>         >
>>         >
>>         >  On 7/2/07, *Tim* <ignored_mailbox at yahoo.com.au
>>         <mailto:ignored_mailbox at yahoo.com.au>
>>         >  <mailto:ignored_mailbox at yahoo.com.au
>>         <mailto:ignored_mailbox at yahoo.com.au>>> wrote:
>>         >
>>         >     On Mon, 2007-07-02 at 19:14 +0530, Rohan Kulkarni wrote:
>>         >      > My motherboard supports hard disk speed of 150MB/s 
>> but i
>>         get only
>>         >      > 15MB/s speed
>>         >
>>         >     Have you double-checked that the figures you're reading at
>>         are bits per
>>         >     second or bytes per second?
>>         >
>>         >     --
>>         >     (This box runs FC5, my others run FC4 & FC6, in case 
>> that's
>>         >     important to the thread.)
>>         >
>>         >     Don't send private replies to my address, the mailbox is
>>         ignored.
>>         >     I read messages from the public lists.
>>         >
>>         >
>>         >
>>         >  Hello,
>>         >            Yes I have checked with the motherboard
>>         specifications.It
>>         >  says that it supports
>>         >            a speed of 150MB/s.It is bytes for second.Though my
>>         hard disk
>>         >  supports native command queing my motherboard does not 
>> support
>>         it.
>>         >
>>         >     --
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>>         >
>>         >
>>
>>         It doesn't matter what speed your motherboard (SATA controller)
>>         supports if the disk speed is slower. What brand/model of disk
>>         do you
>>         have? What kernel version? How are you measuring the disk speed?
>>
>>         Regards,
>>
>>         John
>>
>>
>>
>>     Hello,
>>              I have a Seagate ST3160211AS.It is a Barracuda 160GB hard
>>     disk with a
>>              speed of 7200RPM.It supports upto 300MB/s with Native
>>     Command Queing.I checked the average  speed of copying by copying a
>>              3GB file from one FAT32 partition to another.I got a
>>     average speed of around
>>              15MB/s.I have the kernel 2.6.21-1.3228.fc7
>>                                                              Thanks...
>>
>>
>>
>>       Can anyone please help me...do i need to update to the latest 
>> kernel??or do i need
>>       to download some drivers.
>>
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>>
>>
>>
>
> You don't really have a problem!
>
> Don't confuse the maximum interface transfer speed (150 MB/s) with 
> your disk transfer speed (approx 40-50 MB/s).
>
> When you copy a file, you read the old file, and then you write the 
> new file, rinse and repeat until done. So your transfer speed is going 
> to be approximately 1/2 to disk speed. And now you need to add in the 
> operating system overhead, allocating blocks for the new file, and all 
> the seek time, moving the disk heads between the old file blocks and 
> the new file blocks.
>
> 15 MB/s seems reasonable. On my box, using a single drive, I get a 
> write speed of 30 MB/s for a 3 GB file and a copy speed of 14 MB/s.
>
> Need more speed, get more disks and a raid controller.
>
> Regards,
>
> John
>
>
Don't forget on the Seagate drives to remove the little jumper to enable 
the SATA interface at 3.0Gb/s (assuming your motherboard can support it) 
since Seagate's default setting is with the jumper installed.

ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300)

Jeff