Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi all! I got the following useful pointers in reply to my posting: Diego Julian Remolina wrote: >> The plan: >> >> * Edit /etc/fstab on server A so that /dev/sda[X] gets mounted, >> instead of /dev/md[X]. >> * Power down >> * Take out /dev/sdb (and put aside just in case of a major FUBAR) and > > Before you take out /dev/sdb make sure that it has grub installed and > that you can boot from it. Most of the times people create linux > software raid 1, but only installs grub on hard drive on, and so when > hard drive 2 fails, they cannot boot until they install grub on it as well. Good point! :-) Is grub the only way to do this, or can I use dd to copy the boot-sector from the active boot disk to the other one? >> replace it with an empty disk >> * Boot up from /dev/sda >> * Partition /dev/sdb as follows: >> /boot 100M >> [root] 25G >> /var 20G >> [swap] 5G >> /vservers [remainder] > /dev/sdb7 1G For drbd metadata. > > It is *highly* recommended that you put your metadata in a separate > partition. This will eliminate a few headaches later down the road. Good idea! Will 1GB always be enough? Current docs say 128MB will be used per drbd-partition. Will this remain so? And, something I maybe overlooked in the docs, but: how should the metadata-partition be formatted? will any fs do? which one is recommended? >> On to server B: >> * Power down server A move 1 of its drives to server B. Put an empty >> drive in server A. Reboot server A & resync the RAID partitions >> on-the-fly. >> > > Sounds like a good plan, but why not leave server A up and running and > since your took Drive2 out of server A, then you simply copy the > partitions to one drive in server B and start setting everything up in > server B. That way you are not working on your production server > (server A) putting it at risk of being damaged if you make a mistake. > You can always mount Drive2 from server A read only while in server B if > you are worried about damaging or altering the data and then use rsync > or parted to copy the partitions. So my choices here are: *using mdadm to sync make md-partitions & sync in that way if I feel adventurous (1 typo & the syncing goes in the wrong direction...) * or use rsync/parted with the source-partitions mounted read-only? (I'm not that experienced with parted, but it looks like all I need is equal-sized partitions & the cp-command?) and that is all partitions, except for the vservers & metadata partitions? > At some point when both servers A and > B are up, you rsync all data partitions only (your vservers partition) > from server A to server B and now configure B to be your production > server. You then work on server A to get it the same as B and then > finally start drbd making which ever has current data primary. I'm not sure about the last part here. What work should I have to do on server A...? Or... do you mean I should not do any repartitioning/configuring on server A in the beginning and only take out a drive & resync, and then fully prepare server B? Will rsyncing the data partition, which also contains mysql-databases, cause any problems? Since server B has been made production server, the final step would be telling drbd that Server B = primary & Server A = secondary? That should get vservers/metadata partitions in sync, right? I hope I have formulated my questions/remarks clearly. I'm looking forward to any/all comments! :-) Regards, Evert