[NBLUG/talk] My Server Ideas

[Walter Hansen]

I've been out of love with Raid for sometime. At fist I thought that 
driving a nail through one drive would keep it going. Well sorta, 
sometimes. But probably not. Twin raid drives often fail on the same 
day. And suppose a drive gets corrupted, what are the odds that the 
other drive just mirrors the corruption. One drive fails, just boot the 
other right....maybe.

Of course performance still works and I have set up a pair of 10k drives 
to provide pre-ssd extreme performance.

Anyway these days my ideas are more like this:

Primary SSD drive with LVM
Secondary (larger) drive no LVM also used for backups of other systems.
Once a day or so make a snapshot of the primary and do a rsync of the 
primary.
The plan even includes hot swappable tertiary drives the same size as 
the secondary for backup.

However I'd like to make the secondary drive bootable so if the primary 
fails it could be unhooked and the system would boot of the secondary 
without issue. Then just build a new primary and replace it. I'm 
thinking that a secondary fstab like fstab.secondary setup for the 
alternate boot which doesn't have the LVM setup but the partition setup 
for the secondary. Then just go in and rename fstab fstab.primary and 
rename fstab.secondary fstab, then boot off the secondary.

The primary has a a stock CENTOS partition setup with / and /home on 
separate partitions. For the secondary I setup a boot partition, swap (I 
figured it should have that to boot/run) and a main partition.

I did a dd from the primary /boot to the secondary /boot but was unable 
to install a master boot record on the secondary drive. I tried using dd 
to copy it. Then I tried to use grub to do it. Both failed and I managed 
to corrupt the main grub and had to do a rescue fix for my efforts. The 
tricky bit is probably that the setup for the secondary will have it 
booting as sda or drive 0.

Hmmm I wonder if I could have the grub on the secondary boot go in and 
pull up the secondary fstab.

I think I tried doing something like this with RAID1 before but never 
could get it to work.

The primary drive is under constant use. The secondary drive has light 
usage. I could probably even set it to spin down for even lighter use. 
This setup hopefully avoids the RAID1 double death syndrome (although 
I'm actually using separate technology for the drives.

So am I nuts? Does this make sense?