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

[Volker Armin Hemmann]

On Tuesday 14 December 2010 11:49:00 Dale wrote:
> Mark Knecht wrote:
> > On Tue, Dec 14, 2010 at 9:13 AM, Dale<rdalek1967@×××××.com>  wrote:
> >> Mark Knecht wrote:
> >>> On Tue, Dec 14, 2010 at 8:42 AM, Dale<rdalek1967@×××××.com>    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 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
> >>>>
> >>>> 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
> >>>>
> >>>> 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.
> >>>>
> >>>> Thanks.
> >>>>
> >>>> Dale
> >>>
> >>> The SATA spec allows for hot plugging, so technically yes, but it
> >>> also
> >>> assumes the drives are in some sort of container so that power and
> >>> signals are applied at the right time.
> >>>
> >>> The plug on the front of your case is probably eSATA which looks
> >>> similar but has some small changes. What you want to do is figure
> >>> out
> >>> which of your MB SATA ports are eSATA compatible and then run one of
> >>> those channels to the connector at the front inside your case.
> >>> Typically SATA drives are converted to eSATA external drives by
> >>> putting them in a case you can get at most computer shops for<
> >>> $30 or so.
> >>>
> >>> Hope this helps,
> >>> Mark
> >>
> >> I did hook the eSATA cable that goes to the front of the case to the
> >> eSATA connector on the mobo.  Thing is, I think they are all eSATA
> >> compatible tho.
> >>
> >>   I think that is what I read in the mobo book.  Yea, I read the
> >>   book.  I
> >>
> >> even followed the instructions for the CPU cooler too.  lol
> >>
> >> I was thinking it needed some sort of power for the drive tho.  I
> >> didn't
> >> think it was like USB stuff.
> >>
> >> Thanks for the info.
> >>
> >> Dale
> >
> > One of my MBs had 6 SATA connectors but only two were eSATA compatible.
> >
> > Power for my eSATA drive is supplied by the case.
> >
> > Hope this helps,
> > Mark
>
> It does.  It was the one on the front that made me curious tho.  I have
> used USB for a while but was curious about how it works on the front
> with no power for it.   I think I'll leave that one alone for now.  May
> get brave another day tho.
>
> Thanks.
>
> Dale
>
> :-)  :-)

you seem to have misunderstood Mark. The power is delivered by the harddisks 
case. AKA external power supply. esata has 0 power distribution capabilities.
Always remember: first unplug the sata cable, wait, then power. This allows the 
device to flush the cache.