I want to balance disk space against fault tolerance. I would like fault tolerance to be able to handle multiple disk failures (as I may not be able to afford replacements disks or have the time for weeks possibly)
The main purpose of the home Linux server shall be a place to backup other machines too, store/share large amounts of data. So the data will be re-creatable most of the time. Storage of media (ie backup of my DVD's, Cd's etc)
I had a RAID10 array of 6 x 1.5TB but due to operator incompetence and laziness, I now have 6 empty disks :-) and a clean start.
One of the disks is definitely failing (over 55 error from smartctl and short and long test errors) so it will be sent away for warranty replacement - but I would still like to include it in the final array. Lets call the bad disk /dev/sdc
Machine has 6 sata ports and 2 IDE (with 2 CD drives). Dual Quad core Xeon, 16Gb RAM. And really 1 user most of the time.
[NB I may be able to remove a CD drive and add a 7th IDE disk just for the OS only to separate data/OS] Otherwise plan is to save 100GB partition and put the OS there (maybe mirror between disks)
Option A) RAID 6 sd[abdef], sdc as hot-spare (but gets sent for replacement soon) raid-devices=5 spare=1
Option B) RAID 6 sd[abdef], sdc as missing (but gets sent for replacement soon) raid-devices=6 spare=0
Option C) RAID 10 sd[abdef], sdc as hot-spare (but gets sent for replacement soon) raid-devices=5 spare=1
Option D) RAID 10 sd[abdef], sdc as missing (but gets sent for replacement soon) raid-devices=6 spare=0
Option A is seeming to be the best at the moment because I'll get 4.5TB of space and room for 3 disk failures if I calculate it correctly.
This will all be done with mdadm soft raid.
Which do you recommend or are there better possibilities layouts that I could use?