On Sat, Nov 19, 2016 at 6:22 AM, Dave Howorth <dave@howorth.org.uk> wrote:
On Fri, 18 Nov 2016 23:47:46 -0500 Greg Freemyer <greg.freemyer@gmail.com> wrote:
On Fri, Nov 18, 2016 at 7:44 PM, Florian Gleixner <flo@redflo.de> wrote:
I recommend using mdraid and LVM2.
You can add disks to mdraids and you can change raid levels. See
https://serverhorror.wordpress.com/2011/01/27/migrating-raid-levels-in-linux...
Using md devices as physical devices for a lvm volume adds even more flexibility. If you swap old disks for new ones, you can add the new devices (as new md device) to expand the volume group, use pvmove to move data online to the new devices and then drop old devices from the volume group. Or better: you add new md devices and extend your logical volume.
If you use large disks, use mirrored devices whenever possible. Raid5 is not an option (as Lew already noted) and raid 6 is really slow! Growing a raid6 with another 10TB drive may take days!
So best is to add always 2 devices, create a mirror and add it to the logical volume.
See manpages of mdadm, pvcreate, pvmove, vgextendd, vgreduce, lvextend
Thanks Florian,
I was hoping MDraid / LVM2 was a flexible enough option.
I'd second Florian's recommendation of md and lvm. Have used this for years without problems.
But I'd also second what Per says. RAID is not backup! You need a separate backup as well, definitely offsite and preferably a different technology. But at least a completely separate system with separate disks.
HTH, Dave
Dave, this my backup. No work/analysis done with this copy. But, I still want more than raid 0 for this backup set in the long run. Currently I have at least 1 instance of all this data on 2 USB drives (dozens of drives total, but less than 100 (I think)). Going forward I want to buy 10TB drives (or larger) and consolidate the backups, freeing up the existing USBs for primary storage. I hadn't thought about offsite. Since this data is so static, maybe I should eventually build 2 and use DRDB to replicate to an offsite redundant copy. That actually sounds like some to add to the plan. Greg -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org