[Novalug] grub/booting problems when adding a drive

Jon LaBadie novalugml@jgcomp.com
Wed Jan 26 02:28:36 EST 2011


On Wed, Jan 26, 2011 at 12:10:24AM -0700, Maxwell Spangler wrote:
> On Wed, 2011-01-26 at 00:01 -0500, Jon LaBadie wrote:
> > On one Fedora 14 system I've been trying to add a PATA
> > drive.  This addition causes the drive designations to
> > change and I can't find the correct GRUB incantation
> > to boot the system.  I'll describe the system and then
> > what I've tried.
> > 
> > Currently the systems has 1 PATA optical drive and 2 SATA
> > drives.  The boot, SATA drive is connected to a mainboard
> > interface while the second SATA drive is connected to a
> > separate PCI controller.
> 
> I'm curious why you have a PCI SATA controller - does your mainboard not
> have two (or more) SATA connections?

You may recall a thread on trying to get a SSD drive working.  That
was on this box.  My plan, at that time, was to have the SSD and a
new, large (1.5TB) drive off the mainboard and the PCI card was for
the old drive.  That never panned out so the SSD is now making my
laptop speedier.  After I got the SSD out, I did the new OS install
and just left things as they were.

> I think you will find faster performance to ditch the PCI card and
> connect all SATA drives directly to the mainboard connections.  SATA
> mainboard connections are designed to go directly to the southbridge
> chip at very high speeds even with multiple drives.
> 
> Connecting a fast SATA drive to a PCI bus on the other hand can easily
> saturate the PCI bus and interfere with competing PCI devices (if you
> have any.)  (I'm assuming you meant PCI and not PCIe.)

Yes, PCI.
> 
> Regardless, I think if you benchmark connecting one drive to the SATA
> mainboard and another to the PCI bus vs both on the mainboard the
> mainboard should win.

In very limited testing (mostly hdparm -t) I found significant differences
for the SSD and for the new large drive.  The SSD was almost 50%
slower on the PCI interface (but it formatted and otherwise worked on
that interface), the new 1.5TB drive about 25% slower.  The older drive
was the same speed on either interface, matching the new large drive's
slower PCI interface speed.

-- 
Jon H. LaBadie                  novalugml@jgcomp.com
 JG Computing
 12027 Creekbend Drive		(703) 787-0884
 Reston, VA  20194		(703) 787-0922 (fax)



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