Hello, On Wed, 29 Oct 2014, Carlos E. R. wrote:
On 2014-10-29 08:50, jdd wrote:
may be because you need to use a rescue system any time? with several linux on the same drive it's difficult to guess who is where
I do, but that is not the reason. [..] What is sda one boot, is sdb on the next, and sda becomes one of the externals instead.
That, in my experience, depends on whether the BIOS/UEFI manipulates what is what. I have an external docking station (USB/eSATA, doesn't matter for this). Apart from that, I've got 6 SATA on the AMD SB710 southbridge, 2 SATA on a Marvel 9128 and 2 eSATA on a JMicronJMB362 (both via PCIe on the AMD 770 northbridge) and 2 USB3.0 on a NEC also via PCIe on the AMD770. When I boot from it via grub, all is as usual, with hd0 in grub being the /dev/sda being SATA0 on the SB710. When I change via the BIOS-boot-menu to one of the eSATA or USB ports, that device becomes hd0 and /dev/sda (and IIRC the other port on that chip becomes hd1 and /dev/sdb), regardless of which chip I switch to (Marvel, JMB or the NEC USB one). IIRC my old MoBo/BIOS did not do that, it always presented the devices in the same order.
On some machines the names like sda remain stable, but on many they don't, and can not be made stable. They gave up on the attempts, and invented that other system.
Well, depends on how you boot and select your boot-device ;)
Another reason for using labels or uuids, is that not only you can move around the disks, but that you can move around the partitions! You can add new partitions to the disk, or remove, resize or join some, and both labels and uuids remain untouched, so that booting works the same, and fstab doesn't need to be edited. The partition numbers change, but the names do not.
Yes. Actually, I just recently swapped out a LABEL=FOO (just one partition on that disk) with a new drive. Temporarily named the new partition FOO_NEW, moved the data (or copied? CNR), removed the old drive, put in the new one, ran 'e2label /dev/sdXy FOO', et voila. With stable /dev/sd*, it would be a bit easier (BTDT): just pop in the new drive externally, copy data, switch drives (i.e. remove the old drive on the SATA0-MoBo-Connector, connect the new drive, done (as the SATA0 Connector always got /dev/sda. At least since ahci was compiled in the kernel ;) If modules are involved, you gotta take care of a stable sequence, which is easy enough using the former above/below feature of modprobe. I wrote a little translator script for that[1]. Some samples from my fstab: ### part-by-disk-id+part (stable): /dev/disk/by-id/ata-SAMSUNG_HD204UI_[..]-part1 swap swap defaults,pri=42 0 0 ### part-by-label (stable): LABEL=ROOT_SSD_1 / ext4 acl,user_xattr,noatime,nodiratime,errors=remount-ro 1 1 LABEL=R_HOME /home ext3,ext2 acl,user_xattr,strictatime,errors=remount-ro 1 0 ### image mount (stable): /data/spool/news_reiserfs.img /data/spool/news \ reiserfs loop,acl,user_xattr,strictatime,barrier=flush 0 0 ### tmpfs mount (stable): tmpfs /data/build tmpfs nosuid,size=75% 0 0 #### udev-symlink mounts of /dev/sr0 /dev/cdrom /cdrom auto noauto,ro,user,users 0 0 /dev/dvd /dvd auto noauto,ro,user,users 0 0 /dev/dvdram /dvdram auto noauto,rw,user,users 0 0 ### nfs mount (stable): foo:/ /foo/root nfs defaults,noauto,[..] 0 0 ### by id mount of one USBstick (stable): /dev/disk/by-id/usb-USB_2.0_Flash_Disk_[..]-0:0-part1 \ /usbadata4 auto defaults,user,users,iocharset=iso8859-15,noauto 0 0 ### one of the front-USB2.0-ports by path (stable): /dev/disk/by-path/pci-0000:00:13.2-usb-0:1:1.0-scsi-0:0:0:0-part1 \ /usb6p1 auto defaults,user,users,iocharset=iso8859-15,noauto 0 0 HTH, -dnh [1] a whopping 1330 bytes of awk :) To e.g. always load sata_sil after pata_atiixp: $ echo 'above pata_atiixp sata_sil' | ~/src/modprobe_gen/modprobe_gen ### above pata_atiixp sata_sil install pata_atiixp /sbin/modprobe --ignore-install pata_atiixp && {\ /sbin/modprobe sata_sil;\ } remove pata_atiixp {\ /sbin/modprobe --remove sata_sil;\ }; /sbin/modprobe --ignore-remove --remove pata_atiixp; or the other way around (you could switch the modules too ;) first sata_sil, then pata_atiixp: $ echo 'below pata_atiixp sata_sil' | ~/src/modprobe_gen/modprobe_gen ### below pata_atiixp sata_sil install pata_atiixp {\ /sbin/modprobe sata_sil;\ }; /sbin/modprobe --ignore-install pata_atiixp remove pata_atiixp /sbin/modprobe --ignore-remove --remove pata_atiixp && {\ /sbin/modprobe --remove sata_sil;\ } -- [Mouse problems] So, delete /bin/cat -- I tried that. I had to "rm /bin/cat" nine times before it disappeared. (Gabor Lenart, Mans Rullgard) -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org