[CentOS] raid 5 install

Mon Jul 1 14:48:14 UTC 2019
Warren Young <warren at etr-usa.com>

On Jul 1, 2019, at 7:56 AM, Blake Hudson <blake at ispn.net> wrote:
> I've never used ZFS, as its Linux support has been historically poor.

When was the last time you checked?

The ZFS-on-Linux (ZoL) code has been stable for years.  In recent months, the BSDs have rebased their offerings from Illumos to ZoL.  The macOS port, called O3X, is also mostly based on ZoL.

That leaves Solaris as the only major OS with a ZFS implementation not based on ZoL.

>     1) A single drive failure in a RAID4 or 5 array (desktop IDE)

Can I take by “IDE” that you mean “before SATA”, so you’re giving a data point something like twenty years old?

>     2) A single drive failure in a RAID1 array (Supermicro SCSI)

Another dated tech reference, if by “SCSI” you mean parallel SCSI, not SAS.

I don’t mind old tech per se, but at some point the clock on bugs must reset.

> We had to update the BIOS to boot from the working drive

That doesn’t sound like a problem with the Linux MD raid feature.  It sounds like the system BIOS had a strange limitation about which drives it was willing to consider bootable.

> and possibly grub had to be repaired or reinstalled as I recall

That sounds like you didn’t put GRUB on all disks in the array, which in turn means you probably set up the RAID manually, rather than through the OS installer, which should take care of details like that for you.

>     3) A single drive failure in a RAID 4 or 5 array (desktop IDE) was not clearly identified and required a bit of troubleshooting to pinpoint which drive had failed.

I don’t know about Linux MD RAID, but with ZFS, you can make it tell you the drive’s serial number when it’s pointing out a faulted disk.

Software RAID also does something that I haven’t seen in typical PC-style hardware RAID: marry GPT partition drive labels to array status reports, so that instead of seeing something that’s only of indirect value like “port 4 subunit 3” you can make it say “left cage, 3rd drive down”.