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Re: [opensuse] Confused by hard drive naming/position /dev/sda vs hd0 etc,
  • From: "Carlos E. R." <robin.listas@xxxxxxxxxxxxxx>
  • Date: Mon, 15 Mar 2010 22:35:25 +0100 (CET)
  • Message-id: <alpine.LSU.2.00.1003152140350.16913@xxxxxxxxxxxxxxxx>
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On Sunday, 2010-03-14 at 21:57 -0400, Felix Miata wrote:

0On 2010/03/15 02:27 (GMT+0100) Carlos E. R. composed:

I'm now very wary of doing tests. :-/

What I suggested wouldn't be a very involved "test". Just copy two files to a
stick that you've installed Grub onto, and capture some log files that result
from using AHCI instead of IDE BIOS settings, to see if others'
recommendation to use AHCI has any real payoff.

I don't have any stick with grub on it, nor any free (ie, available) one.


USB is far slower than the HD.

Far slower in this case maybe amounts to 10 seconds at most increase in boot
time. Kernel and initrd only need to be read once per boot. Nothing but those
two, and Grub, need to load from the slower source. After that, all reads and
writes depend on what's been mounted and what if anything you choose to do.

Look, tomorrow (now it is past 2 AM, and I get up at 6) I'll set the
external sata drives to AHCI, and try to boot from the remaining internal
disks, on IDE mode. I'll try to see if the external disks can be found.

Is that good enough for you?

I'm just putting some thoughts to words that might be useful. Nothing I need
to do depends on what you choose to do with your system. :-) That said, I
expect you'll be pleased with what results from your plan for the morning.

Ok, I tested.

In the bios setup screen, in the "standard cmos features" I get the list of disks found (ide mode, the default mode for this board):

sata 1 \
sata 2 |
sata 3 | (C)
sata 4 |
sata 5 |
sata 6 /
ide primary master
ide primary slave
sata 7 \ (B)
sata 8 /
e-sata 1 \
e-sata 2 / (A)



The "integrated peripheral" section, contains these options:

On board E-sata controller enabled
raid mode ide (options: ide, raid, ahci) (A)
Extra raid/ide controller enabled
raid mode ide (options: ide, raid, ahci) (B)
on-chip ata devices
pci ide bus master disabled
on chip sata controller enabled
raid mode ide (options: ide, raid, ahci) (C)

If in this last one I set "ahci" I get a new line:

AHCI devices group

Pressing enter on this one I see

AHCI settings (not enterable)
AHCI CD/DVD boot time out 35 (options: 0, 5, 10,..,35)

AHCI Port 1 [Not detected]
AHCI Port 2 [Not detected]
...
AHCI Port 6 [Not detected]

If I enter any of these ports, I see:

AHCI port 1 Auto (options: auto/not installed)
hard disk smart enabled (options: enabled/disabled)




Now, if I set the group (C) to "ahci", the system does not boot. I get a black screen with a blinking cursor.

If, instead, I set group (A) (two identical 500GB external disks) to ahci, and group (B) to ahci (one 320GB refurbished HD), the system boots, but not normally. After the bios post test, I get:

http://picpaste.com/Imagen0192.jpg

and after I press the key, I get:

http://picpaste.com/Imagen0194.jpg

My guess is that it is scanning for a raid setup.

This is slow, about 20". After this the system boots. All disks are accesable. The one on "sata 1" is /dev/sdd, and the one on "e-sata 2" is now "/dev/sda". Notice that if the external disks are not powered on during boot, sda is sata1 (as it should be). This is why we can no longer use the classical device names in fstab, except on a few lucky systems.

/dev/disk/by-label/Jazz_2 -> ../../sda1

I do a speed test on it (hdparm -tT /dev/sda), and I get:

/dev/sda:
Timing cached reads: 13528 MB in 2.00 seconds = 6772.15 MB/sec
Timing buffered disk reads: 340 MB in 3.00 seconds = 113.19 MB/sec



Now I reboot, and change back the settings to "IDE". I redo the speed test:

/dev/sda:
Timing cached reads: 14162 MB in 2.00 seconds = 7089.54 MB/sec
Timing buffered disk reads: 340 MB in 3.00 seconds = 113.17 MB/sec



Thus, your claims that I would get a speed advantage using AHCI is not valid on my system. And I actually can plug/unplug it "hot". The log is quite verbose:

hd power off event:

Mar 15 22:13:42 Elessar kernel: [ 4958.121689] ata1: exception Emask 0x10 SAct
0x0 SErr 0x990000 action 0xe frozen
Mar 15 22:13:42 Elessar kernel: [ 4958.121700] ata1: irq_stat 0x00400000, PHY
RDY changed
Mar 15 22:13:42 Elessar kernel: [ 4958.121707] ata1: SError: { PHYRdyChg 10B8B
Dispar LinkSeq }
Mar 15 22:13:42 Elessar kernel: [ 4958.121716] ata1: hard resetting link
Mar 15 22:13:43 Elessar kernel: [ 4958.844030] ata1: SATA link down (SStatus 0
SControl 300)
Mar 15 22:13:48 Elessar kernel: [ 4963.844011] ata1: hard resetting link
Mar 15 22:13:48 Elessar kernel: [ 4964.149026] ata1: SATA link down (SStatus 0
SControl 300)
Mar 15 22:13:48 Elessar kernel: [ 4964.149042] ata1: limiting SATA link speed
to 1.5 Gbps
Mar 15 22:13:53 Elessar kernel: [ 4969.149010] ata1: hard resetting link
Mar 15 22:13:54 Elessar kernel: [ 4969.455025] ata1: SATA link down (SStatus 0
SControl 310)
Mar 15 22:13:54 Elessar kernel: [ 4969.455039] ata1.00: disabled
Mar 15 22:13:54 Elessar kernel: [ 4969.455052] ata1: EH complete
Mar 15 22:13:54 Elessar kernel: [ 4969.455060] ata1.00: detaching (SCSI 0:0:0:0)
Mar 15 22:13:54 Elessar kernel: [ 4969.455824] sd 0:0:0:0: [sda] Synchronizing
SCSI cache
Mar 15 22:13:54 Elessar kernel: [ 4969.455879] sd 0:0:0:0: [sda] Result:
hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Mar 15 22:13:54 Elessar kernel: [ 4969.455889] sd 0:0:0:0: [sda] Stopping disk
Mar 15 22:13:54 Elessar kernel: [ 4969.455903] sd 0:0:0:0: [sda] START_STOP
FAILED
Mar 15 22:13:54 Elessar kernel: [ 4969.455910] sd 0:0:0:0: [sda] Result:
hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK

hd power on event:

Mar 15 22:17:47 Elessar kernel: [ 5202.656925] ata1: exception Emask 0x10 SAct
0x0 SErr 0x4000000 action 0xe frozen
Mar 15 22:17:47 Elessar kernel: [ 5202.656937] ata1: irq_stat 0x00000040,
connection status changed
Mar 15 22:17:47 Elessar kernel: [ 5202.656944] ata1: SError: { DevExch }
Mar 15 22:17:47 Elessar kernel: [ 5202.656953] ata1: hard resetting link
Mar 15 22:17:53 Elessar kernel: [ 5208.582023] ata1: SATA link up 3.0 Gbps
(SStatus 123 SControl 300)
Mar 15 22:17:53 Elessar kernel: [ 5208.582039] ata1.00: link online but device
misclassifed
Mar 15 22:17:53 Elessar kernel: [ 5208.582042] ata1: link online but 1 devices
misclassified, retrying
Mar 15 22:17:53 Elessar kernel: [ 5208.582049] ata1: reset failed (errno=-11),
retrying in 5 secs
Mar 15 22:17:57 Elessar kernel: [ 5212.656012] ata1: hard resetting link
Mar 15 22:17:58 Elessar kernel: [ 5213.584020] ata1: SATA link up 3.0 Gbps
(SStatus 123 SControl 300)
Mar 15 22:17:58 Elessar kernel: [ 5213.587938] ata1.00: ATA-8: ST3500418AS,
CC38, max UDMA/133
Mar 15 22:17:58 Elessar kernel: [ 5213.587947] ata1.00: 976773168 sectors,
multi 0: LBA48 NCQ (depth 31/32)
Mar 15 22:17:58 Elessar kernel: [ 5213.589250] ata1.00: configured for UDMA/133
Mar 15 22:17:58 Elessar kernel: [ 5213.589262] ata1: EH complete
Mar 15 22:17:58 Elessar kernel: [ 5213.589358] scsi 0:0:0:0: Direct-Access
ATA ST3500418AS CC38 PQ: 0 ANSI: 5
Mar 15 22:17:58 Elessar kernel: [ 5213.589548] sd 0:0:0:0: Attached scsi
generic sg0 type 0
Mar 15 22:17:58 Elessar kernel: [ 5213.589565] sd 0:0:0:0: [sda] 976773168
512-byte logical blocks: (500 GB/465 GiB)
Mar 15 22:17:58 Elessar kernel: [ 5213.589631] sd 0:0:0:0: [sda] Write Protect
is off
Mar 15 22:17:58 Elessar kernel: [ 5213.589639] sd 0:0:0:0: [sda] Mode Sense: 00
3a 00 00
Mar 15 22:17:58 Elessar kernel: [ 5213.589666] sd 0:0:0:0: [sda] Write cache:
enabled, read cache: enabled, doesn't support DPO or FUA
Mar 15 22:17:58 Elessar kernel: [ 5213.589856] sda: sda1 sda2 < sda5 sda6 sda7
>
Mar 15 22:17:58 Elessar kernel: [ 5213.652364] sd 0:0:0:0: [sda] Attached SCSI
disk


Notice the "SATA link up 3.0 Gbps" above, and the partitions found correctly, so hotpluging works as it should. What could I gain by setting ahci mode in the bios? A failed boot, perhaps having to boot from a usb stick, no speed advantage... All sort of problems.


My guess is that it is some type of RAID configuration, not really AHCI setup. And if it is AHCI, the bios can not find the disks, specially the group (C), the internal main disks. Perhaps it needs sometype of special disk for it to work on this system.


And as far as I can see, I got the latest bios. I don't know if it came that way, or the chaps than assembled my computer did it for me. They took their time...


- -- Cheers,
Carlos E. R.
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