Do Dell perc 6i cards support online expansion of a raid 1 array when both drives have been replaced with larger ones?

For example the the Logical Drive 0 (LDO) has two member 73gb drives.

We have two new 147GB drives available and inserted into the spare slots of the server. (not worried about final drive location in system)

Can I remove each 73gb and replace it with a 147gb and then grow the raid 1 array using the MegaCli tools (version 4.00.11)?

Will the controller support online expansion?

What command switches are required to complete the reconstruction/grow/expand if supported?

Alternatively I will have to create a new LD on the controller (2x 147gb raid1), pvmove the data, and dd /boot over and reinstall grub etc.

  • 1
    Reviewing the LSI docs I can see I can add a drive to the array or convert from say raid1 to raid5 but no official word on expanding/growing an array. The dell forums have a post indicating you can re-sync with new drives to the array. Then delete the array via the webbios once both larger drives are in use but still the old smaller array size. Then recreate it with the new size without and init.
    – pjd
    Sep 24, 2009 at 6:21
  • Can you point me to the doc please? Nov 5, 2009 at 5:09
  • 1
    It just happens that I'm performing this exact operation on a server with a PERC 5i right now - can't do it online from what I've found but I've been following this: unixwiz.net/techtips/dell-perc6-extend.html
    – James Yale
    Oct 20, 2011 at 13:13
  • Just to update I've now deleted/recreated the virtual disk, expanded the partition and the extra space is now usable.
    – James Yale
    Oct 20, 2011 at 14:00
  • @James: But you did not change the stripe size, right?
    – Nils
    Nov 9, 2011 at 19:35

2 Answers 2


That doesn't seem possible in PERC 6/i controllers.

You could break the RAID-1 volume, replace the drive with a bigger one and create a RAID-0 volume on it. Migrate the data, do the software configuration and replace the remaining disk. Not as easy as online expansion though.

You don't mention which software you use but if it is ZFS, you could follow the suggestion above and attach the new RAID-0 volume to the existing disk. Later you destroy the degraded RAID-1 volume, create a RAID-0 on top of the new disk and attach it to the disk. It's very easy.


From what I`ve derived from James comment it seems you can use the same method as with any virtual disk: Shut down the OS, resize the disk without changing vital parameters (the geometry of the vdisk and stripe size have to stay the same). So if your vdisk geometry after the new size has just more cylinders it should work.

But - this is offline, of course.

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