Re: HELP! Re: How to fix I/O errors? (SOLVED)

[Bob Weber <bobrweber@gmail.com>]

I use raid 1 also for the redundancy it provides.  If I need a backup I just connect a disk, grow each array and add it to the array (I have 3 arrays for /, /home and swap).  It syncs up in a couple hours (depending on size of the array).  If you have grub install itself on the added disk you have a bootable copy of your system (mdadm will complain about a degraded array).  I then remove the drive and place it in another outbuilding in case of fire.  You can even use a external USB disk housing for the drive to keep from shutting down the system.  The sync is MUCH slower ... just coma back the next day and you will have your backup.  You then grow each array back to the number of disks you had before and all is happy again.  Note that this single disk backup will only work with raid 1.

...Bob

On 02/11/2017 10:42 PM, Marc Shapiro wrote:

On 02/11/2017 05:22 PM, Marc Auslander wrote:

You didn't ask for advice so take it or ignore it.

IMHO, in this day and age, there is no reason not to run raid 1.  Two
disks, identially partitioned, each parition set up as a raid 1
partition with two copies.

When a disk dies, you remove it from all the raid partitions, pop in a
new disk, partition it,  add the new partitions back into the raid
partitions and raid rebuilds the copies.

Except for taking the system down to replace the disk (assuming you
don't have a third installed as a spare) you just keep running as if
nothing has happened.

I had been considering using raid 1 and I have not yet ruled it out entirely.  I have never used raid and have been reading up on it over the past couple of weeks.  AIUI you can use LVM over raid.  Is there any actual advantage to this?  I was trying to determine the advantages of using straight raid, straight LVM, or LVM over raid.  If I decide, later, to use raid, how dificult is it to add to a currently running system (with, or without LVM)?


Marc