[lfs-support] Q: Is the map between physical SATA disks and GRUB2's hdn fixed?
Jeremy Henty schrieb: Can I be sure that GRUB2's hd0, hd1 etc. will always correspond to the same physical SATA connectors on the motherboard, no matter what hardware I plug in? (I know from experience that /dev/sda does not always map to the same connector.) If not, how can I find out the mapping after booting from a live CD? Or can I drop into the BIOS and asssume that it lists the drives in hd0, hd1 ... order? short: no, you can't. long: i'm using mobile racks in my dev systems. usually i just have 2, but in my 'big iron' i use a icy-dock 3disk cabinet (mb 973sp) which is connected to the 3 first sata-connectors. on the 4th i have the dvd. if i just have 1 disk inserted, it will always be hd0 and /dev/sda, independent which of the 3 slots the disk is in. if i insert 2 disks, the topmost (slot 1 or 2) will be hd0, and the lower one (slot 2 or 3) will be hd1. no matter how i populate (1+2, 1+3 or 2+3) the topmost is hd0/sda, the lower one hd1/sdb. inserting a 'next' disk while having lfs up will give the next letter, thus inserting a second will be /dev/sdb and the third /dev/sdc, independent of which slot i use. even worse #1: booting with 3 disks, i get hd0,hd1 and hd2 with grub, and /dev/sda, sdb and sdc. hd0/sda will be the topmost disk in the cabinet. unmounting and removing sdb and sdc, waiting some time and then reinserting sdc (the 3thd) will show it now as sdb, insering the former sdb a little later will show it as sdc! even worse #2: the mainboard has an additional marvel chip with another 2 sata ports. i have another 3.5 plus a 2.5 bay attached to this ports. if i just have inserted the 2.5 disk, grub assignes hd0, lfs uses /dev/sde. lfs will use sde and sdf for the 2 ports. having inserted just one it will be sde, independend wether i have the 2.5 or 3.5 bay filled on startup. i guess the onchip driver is loaded first (assigning sda-scd) and the marvel second (assigning sde+f). grub seems to enumerate all available ports just enumerating the found devices without leaving any 'whole'. tobias -- http://linuxfromscratch.org/mailman/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/lfs/faq.html Unsubscribe: See the above information page
Re: [lfs-support] Q: Is the map between physical SATA disks and GRUB2's hdn fixed?
At 20.07.2012 22:16, Jeremy Henty wrote:
Can I be sure that GRUB2's hd0, hd1 etc. will always correspond to the
same physical SATA connectors on the motherboard, no matter what
hardware I plug in? (I know from experience that /dev/sda does not
always map to the same connector.) If not, how can I find out the
mapping after booting from a live CD? Or can I drop into the BIOS and
asssume that it lists the drives in hd0, hd1 ... order?
You can avoid all the hassle about device mapping by using UUID's.
In parallel to my LFS, I have an Ubuntu installed. I use the grub
bootloader from my LFS for it was the first system on the disk.
In the past Ubuntu sometimes hiccup'ed on the device mapping I used in
my grub.cfg due to some updates I got for Ubuntu.
That was until I found out about UUIDs. Every partition on a disk gets a
unique UUID when formated. By using this UUID in grub.cfg I got rid of
any problems Ubuntu had with device mapping.
Here is a snippet from my grub.cfg
### BEGIN /etc/grub.d/17_ubuntu64 ###
menuentry Ubuntu 10.04 LTS 64 Bit {
insmod ext2
set root=UUID=9d35bf11-528c-4fa7-b838-ec734d13ba73
search --no-floppy --fs-uuid --set
9a36bf12-518a-4fb7-b238-ec714d13ca73
echo Loading Ubuntu ...
linux /vmlinuz root=UUID=9a36bf12-518a-4fb7-b238-ec714d13ca73
ro splash quiet
initrd /initrd.img
}
You can even use UUID inside /etc/fstab
Again a snippet from my fstab:
# Begin /etc/fstab
# file system mount-point typeoptions dumpfsck
[...]
UUID=2ae6b852-0a23-4731-95a8-e4543603113b /mnt/BigStore ext3
noauto,user 0 0
[...]
Maybe you can use this as well to get rid of any device mapping hassle.
Regards,
Dan
--
http://linuxfromscratch.org/mailman/listinfo/lfs-support
FAQ: http://www.linuxfromscratch.org/lfs/faq.html
Unsubscribe: See the above information page
Re: [lfs-support] Q: Is the map between physical SATA disks and GRUB2's hdn fixed?
Bruce Dubbs wrote: I can't really answer your question for sure, but on my motherboard, I have four SATA sockets. In adding a new drive, the designation, sdb, sdc, etc, seemed to go with the particular socket. The BIOS also seemed to map to the particular socket too. I have four SATA sockets too and I have definitely seen the map from socket to /dev/sd? change depending on what hardware was plugged in where. This is interesting - I burned a grub rescue disk and it thought my first hard drive was hd1 , not hd0 ? The root= parameter to linux was still /dev/sda2 , but after booting grub on the disk reports the same device map as before, namely hd0 - /dev/sda . Surprising! Regards, Jeremy Henty -- http://linuxfromscratch.org/mailman/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/lfs/faq.html Unsubscribe: See the above information page
Re: [lfs-support] Q: Is the map between physical SATA disks and GRUB2's hdn fixed?
On Fri, 20 Jul 2012 23:10:25 +0100 Ken Moffat zarniwh...@ntlworld.com wrote: Personally, I would never trust a BIOS writer to do things correctly, nor a manufacturer of affordable motherboards to do things straightforwardly - on one of my current boxes, the connector where I happened to connect the DVD drive uses a different SATA driver from the other connectors ;) You must have been very happy when you figured it out. ;) LOL -- Fourth law of programming: Anything that can go wrong wi sendmail: segmentation violation - core dumped -- http://linuxfromscratch.org/mailman/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/lfs/faq.html Unsubscribe: See the above information page
Re: [lfs-support] Q: Is the map between physical SATA disks and GRUB2's hdn fixed?
On Sat, Jul 21, 2012 at 06:01:36PM +0200, Aleksandar Kuktin wrote: On Fri, 20 Jul 2012 23:10:25 +0100 Ken Moffat zarniwh...@ntlworld.com wrote: Personally, I would never trust a BIOS writer to do things correctly, nor a manufacturer of affordable motherboards to do things straightforwardly - on one of my current boxes, the connector where I happened to connect the DVD drive uses a different SATA driver from the other connectors ;) You must have been very happy when you figured it out. ;) LOL 8) : your LOL is the relevant comment -- das eine Mal als Tragödie, das andere Mal als Farce -- http://linuxfromscratch.org/mailman/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/lfs/faq.html Unsubscribe: See the above information page
[lfs-support] Q: Is the map between physical SATA disks and GRUB2's hdn fixed?
Can I be sure that GRUB2's hd0, hd1 etc. will always correspond to the same physical SATA connectors on the motherboard, no matter what hardware I plug in? (I know from experience that /dev/sda does not always map to the same connector.) If not, how can I find out the mapping after booting from a live CD? Or can I drop into the BIOS and asssume that it lists the drives in hd0, hd1 ... order? Regards, Jeremy Henty -- http://linuxfromscratch.org/mailman/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/lfs/faq.html Unsubscribe: See the above information page
Re: [lfs-support] Q: Is the map between physical SATA disks and GRUB2's hdn fixed?
Jeremy Henty wrote: Can I be sure that GRUB2's hd0, hd1 etc. will always correspond to the same physical SATA connectors on the motherboard, no matter what hardware I plug in? (I know from experience that /dev/sda does not always map to the same connector.) If not, how can I find out the mapping after booting from a live CD? Or can I drop into the BIOS and asssume that it lists the drives in hd0, hd1 ... order? I can't really answer your question for sure, but on my motherboard, I have four SATA sockets. In adding a new drive, the designation, sdb, sdc, etc, seemed to go with the particular socket. The BIOS also seemed to map to the particular socket too. I would start with the assumption that the mapping is fixed until I had evidence otherwise. -- Bruce -- http://linuxfromscratch.org/mailman/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/lfs/faq.html Unsubscribe: See the above information page
Re: [lfs-support] Q: Is the map between physical SATA disks and GRUB2's hdn fixed?
On Fri, Jul 20, 2012 at 09:16:13PM +0100, Jeremy Henty wrote: Can I be sure that GRUB2's hd0, hd1 etc. will always correspond to the same physical SATA connectors on the motherboard, no matter what hardware I plug in? (I know from experience that /dev/sda does not always map to the same connector.) If not, how can I find out the mapping after booting from a live CD? Or can I drop into the BIOS and asssume that it lists the drives in hd0, hd1 ... order? I was going to reply to Bruce's reply, noting that over the years I've seen drives move around across kernel versions. Then I realised that you were really talking about grub (so, whichever drive is /dev/sda as far as the kernel is concerned has little or no correspondence with what grub thinks). If you have to boot to a live CD to fix things up, I would run grub-mkdevicemap to see what it reports. Of course, if you have to reinstall grub, you install it to /dev/sda or wherever, using what the current kernel thinks the drives are called [ see dmesg ]. Personally, I would never trust a BIOS writer to do things correctly, nor a manufacturer of affordable motherboards to do things straightforwardly - on one of my current boxes, the connector where I happened to connect the DVD drive uses a different SATA driver from the other connectors ;) For the non-root filesystems, in /etc/fstab I use LABEL= [ man e2label - not sure if that would work with btrfs or xfs ]. ĸen -- das eine Mal als Tragödie, das andere Mal als Farce -- http://linuxfromscratch.org/mailman/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/lfs/faq.html Unsubscribe: See the above information page
