i just enlarged the sda and sdb partitions underneath /boot, which broke their raid1 association, and then learned at grub rescue that the centos7/grub2 mbr indeed looks for the raid device, not just an underlying partition, so i wonder if sda were dead if perhaps it might still just work, if all i do is tell the bios to boot sdb. On Thu, Jan 11, 2018 at 8:10 PM, Nathan O'Brennan <plugaz at codezilla.xyz> wrote: > I did try this in Centos 7. My sda failed and I had to do some messing to > get it to boot as degraded, however it was possible. If I remember > correctly I had to switch sata cables so sdb looked like sda and I had just > happened to manually install the boot onto both mbrs. In the end I put a > third drive in just for the OS and boot so I could keep my raid volumes > completely separated. > > In a pinch you can also boot using Kali or something similar and manually > mount the degraded array if you need to pull data off. > > > On 2018-01-11 16:07, gregrwm wrote: > > my setup is sda and sdb are partitioned identically, boot is raid1/ext3, > swap is raid1, root is raid1/lvm/ext4, each raid1 has a partition on sda > and a partition on sdb. > > if sda goes south, will centos7 still boot? it won't work unless the sdb > mbr points to the sdb member of /boot, which means the sdb mbr would not be > an exact copy of the sda mbr. > > i kind of expect it to be more simpleminded and less friendly such that it > will only work if sda is removed and sdb becomes addressable as sda. > > or perhaps the mbr is smarter than i expect and looks for a UUID, in which > case it would work either way. > > has anyone actually tried this in centos7? > > -- this concludes test 42 of big bang inflation dynamics. in the advent of an actual universe, further instructions will be provided. 000000000000000000000042 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mailman.mn-linux.org/pipermail/tclug-list/attachments/20180112/7b0ae524/attachment.html>