On 01/22/2016 04:55 PM, Paul van der Vlis wrote: > Hello, > > I want to put bigger disks into my server. What I want to do is replace > the first disk, rebuild the raid, replace the second disk, rebuild the > raid. The machine has two disks, sda and sdb. > > But, when I replace a disk, it gets a new device name. E.g. /dev/sdb > becomes /dev/sdc. After a reboot it's good again, but I prefer not to > reboot this machine! > > Is there a way to get the correct device name? No. Device names are assigned in the order they are encountered after boot, and that order is not guaranteed by the kernel. You should never depend on those names. When a device name is fully disconnected, modern kernels will recycle the name at the next opportunity. You must be using a hotplug-enabled driver. For most motherboards, turning on "AHCI" mode in the BIOS on those sata ports is all you need. > When not: > Is it maybe an idea too add the wrong device name to the md-device? > mdadm /dev/md0 -a /dev/sdc1 > Then replace /dev/sda what becomes /dev/sdd: > mdadm /dev/md0 -a /dev/sdd1 > Then restore grub on both disks (with "--recheck" ??) > But what will happen after a reboot later? Will the md-device be > restored with the old names? MD stores signatures in the devices it uses that identify them for later assembly. It does not depend on the device name, though it is recorded in the superblock as a "last connected as" kind of indicator. In general, you should not rely on device names in your system configuration. UUIDs and filesystem labels were implemented specifically to avoid this problem. Phil -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
