Re: [gentoo-user] Questions about SATA and hot plugging.

[Helmut Jarausch]

On 12/14/10 17:42:40, Dale wrote:
> Hi,
>
> I got one more hard drive to move over and it is SATA.  Question one,
> can the new mobo's do hot plugging for SATA drives?  I have a plug on
> the front of the case and was wondering since it is on the front if
> they

If this is an eSATA connection then it works just fine out of the box.
It's helpful to write some UDEV rule e.g. in /etc/udev/rules.d/10-
local.rules, e.g.
SUBSYSTEMS=="scsi", ATTRS{model}=="WDC WD10EADS-65L", SYMLINK="WDExt%n"
which generates the /dev/WDExt ... /devWDExt4 devices if there are
e.g. 4 partitions on that drive. Thus you can write a fixed entry
in your fstab using these devices.

> can be hot swapped or if I need to shutdown then hook it up.  If I
> can
>
> hot swap, where does the power come from?  I know the drives I put in
> the case have a separate power connection.  How's that work exactly?
> Is
> that just for external drives that have their own power?
>
> I have two dries in here already.  One I bought and one that was
> donated.  This is what hdparm reports:
>
> fireball ~ # hdparm -tT /dev/sda
>
> /dev/sda:
>   Timing cached reads:   6788 MB in  2.00 seconds = 3395.32 MB/sec
>   Timing buffered disk reads:  328 MB in  3.01 seconds = 109.06 MB/
> sec
> fireball ~ # hdparm -tT /dev/sdb
>
> /dev/sdb:
>   Timing cached reads:   6736 MB in  2.00 seconds = 3367.58 MB/sec
>   Timing buffered disk reads:  324 MB in  3.01 seconds = 107.69 MB/
> sec

Exactly the same here, the external SATA drive is even slower
/dev/sdd:
 Timing cached reads:   7498 MB in  2.00 seconds = 3750.67 MB/sec
 Timing buffered disk reads: 262 MB in  3.02 seconds =  86.70 MB/sec

> fireball ~ #
>
> Is that about normal?  The mobo is 3Gbs/sec and the drives are too.
> Shouldn't they be faster than that?  I read at one time that SATA is
> basically plug up and it works.  Just checking if there is a setting
> I
>
> need to change.
>
> Related to the above, in the BIOS, it is set to Native IDE.  Should
> that
> be set to AHCI instead?  Is that why it is slower than expected?  Is
> that good to go with Linux as well?  I have this set in the kernel
> and
>
> built in as usual:
>
> AHCI SATA support

I'have configured my BIOS like that. It's working just fine.

>
> Let me know if I am somewhat right on anything.  Oh, I decided to
> name
>
> the new rig fireball instead of lightening.  ;-)  You may notice that
> in
> the paste up above.
>
Helmut.