I have a Dell r710 running Debian and just got it tuned to my use. It boots from a RAID 5 array of 4x300gb SAS drives. I have just converted some 600gb NetApp drives to 512 sector and they are recognised. How can I migrate the entire system from 4x300gb drives to 4x600gb drives without data loss and messing up the OS from booting? Of course I want the resultant array to make full availability of the storage size increase.

Is it possible to swap one disk at a time using the RAID bios to rebuild the array? After all there is one disk redundancy.

I saw this thread: community.spiceworks.com/topic/… and wondered if this would work in my case:

replace 1 disk a larger disk let RAID rebuild replace another disk with a larger disk let RAID rebuild replace last disk with a larger disk let RAID rebuild At this point, the controller should allow you to expand the vdisk.

I have eight bays in total. the other four store media files so could be commented out of fstab temporarily and removed if thats the better way to go.

Also, the original running 4x300gb is not full: 428gb free out of 788gb

  • Hardware or Software controller? Battery Backed Write Cache? – Rick James Dec 12 '19 at 18:37

It is highly recommended that you do not replace drives in a hardware array with anything but exactly the same model, often even down to the same BIOS/firmware on the drives.

If you have the spare bays, then create a new array and clone/image the OS over to it. If you do not have the bays available, what I recommend is that you clone your OS drive to a single larger disk (USB HDD, whatever works), confirm its viability, and then rebuild the array and clone/image over to the new array.

If you're running a software RAID array, then whether you can swap a drive at a time will depend on the tolerance for drive differences in the software you're using. My understanding is that Linux MD (mdadm) is very tolerant. Btrfs is extremely tolerant of different disks. But again, it's always recommended to backup your data before any operations like this.

  • hi, thanks for the suggestion. i have created another raid 5 4x600gb in the other bays and used 'dd if=/dev/sda1 of=/dev/sdb1' to copy the partition (after shrinking on gparted to eliminate white space). trouble is the cloned array will not boot, nor recognised as a bootable device on f11 boot menu. i am on bios boot because uefi never seems to boot anything anyway. P.S. i even tried swapping the array to the original bays, raid bios sees the vd fine. – Ed Kemp Dec 12 '19 at 21:49
  • You'll need to dd /dev/sda to /dev/sdb, sda1 and sdb1 are just partitions whereas sda and sdb are the entire disk. As a result, you've missed the boot loader. – DevinM Dec 12 '19 at 21:54

ok i did the big one:

dd if=/dev/sda of=/dev/sdb

from a live distro, then expanded to fill disk using gparted.

btw, it took 2 days.

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