I've noticed that one of the drives has "unassigned" status. Does it mean that it's a spare disk?

# hpacucli controller all show config

Smart Array P410i in Slot 0 (Embedded)    (sn: 50014380143EC650)

   array A (SAS, Unused Space: 0 MB)

      logicaldrive 1 (1.6 TB, RAID 5, OK)

      physicaldrive 1I:1:1 (port 1I:box 1:bay 1, SAS, 900.1 GB, OK)
      physicaldrive 1I:1:2 (port 1I:box 1:bay 2, SAS, 900.1 GB, OK)
      physicaldrive 1I:1:3 (port 1I:box 1:bay 3, SAS, 900.1 GB, OK)


      physicaldrive 1I:1:4 (port 1I:box 1:bay 4, SAS, 900.1 GB, OK)

   SEP (Vendor ID PMCSIERA, Model  SRC 8x6G) 250 (WWID: 50014380143EC65F)

# hpacucli controller slot=0 physicaldrive all show status

   physicaldrive 1I:1:1 (port 1I:box 1:bay 1, 900.1 GB): OK
   physicaldrive 1I:1:2 (port 1I:box 1:bay 2, 900.1 GB): OK
   physicaldrive 1I:1:3 (port 1I:box 1:bay 3, 900.1 GB): OK
   physicaldrive 1I:1:4 (port 1I:box 1:bay 4, 900.1 GB): OK

How I can safely add it to this existing array?


Hi, I've successfully added the fourth drive to the array. I'm trying to extend the logical drive now:

hpacucli ctrl slot=0 ld 1 modify size=max
  • and I received the following warring:

    Warning: Extension may not be supported on certain operating systems. Performing extension on these operating systems can cause data to become inaccessible. See ACU documentation for details. Continue?

I'm running CentOS 6.3 - where I can check if CentOS supports this?

If it does and I will extend the logical drive on the RAID card do I still have to create a new partition, resize physical volume and extend the logical volume on the OS itself to be able to use this extra space?


# df -h
Filesystem            Size  Used Avail Use% Mounted on
                       20G  6.9G   12G  37% /
tmpfs                  71G     0   71G   0% /dev/shm
/dev/sda1             485M   89M  371M  20% /boot

# pvs
  PV         VG      Fmt  Attr PSize  PFree  
  /dev/sda2  vg_01 lvm2 a--  24.00g      0 
  /dev/sda3  vg_02  lvm2 a--   1.61t 702.17g

# vgs
  VG      #PV #LV #SN Attr   VSize  VFree  
  vg_02    1   8   0 wz--n-  1.61t 702.17g
  vg_01   1   2   0 wz--n- 24.00g      0
  • What's your goal? a 4-disk RAID5 array? (I'd recommend not using RAID5 with those drive sizes).
    – ewwhite
    Nov 21, 2012 at 23:26
  • Hi, yes I would like to have 4-disks in RAID 5. Why you wouldn't recommend this?
    – HTF
    Nov 21, 2012 at 23:29
  • 1
    Drive failure during reboot of a failed RAID5 arrays is not as uncommon as desired. Larger drives take longer to rebuild (well, there is more data to rebuild so this is logical) and chances of finding an error before a rebuild is complete are non-zero. -- Thus general advise is not to use large disks in RAID 5 (or if they fail, just copy the changes since the last backup and restore from backup)>
    – Hennes
    Nov 21, 2012 at 23:38
  • Also, you make NO mention of the operating system you're using.
    – ewwhite
    Nov 22, 2012 at 7:18
  • I'm using CentOS.
    – HTF
    Nov 22, 2012 at 7:31

1 Answer 1


In order to just add the disk and make a 4-disk RAID5 array, you'll need to run:

ctrl slot=0 ld 1 add drives=1I:1:4

That will add the disk, redistribute data across the array and expand the logical drive. Here's a cheat-sheet.

You do have other options, like adding the drive to the array and carving out a new logical drive of the unused space, or with an entirely different RAID level. These are very flexible controllers.

Either way, the line above will accomplish what you want.

As for the RAID5 objection, here's an explanation. These are enterprise SAS disks, so you'll be okay... but in general, people are moving away from RAID5 as a recommended drive RAID level as disk sizes increase.

  • Could you please confirm that I can do it on a live server and all data will be preserved without any interruption to the service?
    – HTF
    Nov 22, 2012 at 7:02
  • 1
    Yes and yes, assuming you have a battery or flash-backed cache module on the array controller.
    – ewwhite
    Nov 22, 2012 at 7:17
  • I've added some more info to my original question, may I ask you to have a look?
    – HTF
    Nov 26, 2012 at 23:11
  • Yeah, you can extend. Ignore the warning. The rest depends on your disk/partition layout. Show the output of df -h. But if you're using LVM, you will need to extend the volume at the OS level.
    – ewwhite
    Nov 26, 2012 at 23:41
  • Thanks for reply. I've update the main question with requested info.
    – HTF
    Nov 27, 2012 at 7:05

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