Inactive array – mdadm: Cannot get array info for /dev/md126

Replacing a disk maybe sometimes challenging, especially with software RAID. If the software RAID1 went inactive this article might be for you!
Booting from a LIVECD or a rescue PXE system and all RAID devices got inactive despite the loaded personalities. We have similar article on the subject – Recovering MD array and mdadm: Cannot get array info for /dev/md0

livecd ~ # cat /proc/mdstat 
Personalities : [raid6] [raid5] [raid4] [raid0] [raid1] [raid10] [linear] [multipath] 
md125 : inactive sdb3[1](S)
      1047552 blocks super 1.2
md126 : inactive sdb1[1](S)
      52427776 blocks super 1.2
md127 : inactive sdb2[1](S)
      16515072 blocks super 1.2
unused devices: <none>

Despite the personalities are loaded, which means the kernel modules are successfully loaded – “[raid6] [raid5] [raid4] [raid0] [raid1] [raid10] [linear] [multipath] “. Still, something got wrong and the device’s personality is unrecognized and is inactive state.
A device in inactive state cannot be recovered and it cannot be added disks:

livecd ~ # mdadm --add /dev/md125 /dev/sda3
mdadm: Cannot get array info for /dev/md125

In general, to recover a RAID in inactive state:

  1. Check if the kernel modules are loaded. If the RAID setups are using RAID1, the “Personalities” line in /proc/mdstat should include it as “[raid1]”
  2. Try to run the device with “mdadm –run”
  3. Add the missing device to the RAID device with “mdadm –add” if the status of the RAID device goes to “active (auto-read-only)” or just “active”.
  4. Wait for the RAID device to recover.

Keep on reading!

Smart Array P440 – enable or disable HBA mode using Smart Storage Administrator

As a continuation of our series about HPE Smart Array P440 controller here how you can enable HBA mode of your controller. There are various scenarios why you may want to enable HBA such as:

  • JBOD mode -to use the disks in a sophisticated file system like ZFS, brtfs and more (or LVM, device mapper logical devices). You may have more features in the created logical device (or file system) – caching or managing the disks and so on
  • not using the cache (RAM) of the controller, so it may lower the risk of data loss caused by power outages
  • more platform independent when using software RAID / device mapper devices. When you create virtual drives in hardware mode, you must use only this type of proprietary controller or some compatible of the same company. When using software solution like software RAID or LVM (and the controller is in JBOD) you can move the disks with no problem to other hardware without the hardware controller.
  • * Some old controller (not this one) might have problems with SSDs such as timings when the disks start; when failing a disk (the SSD would probably fail with read-only, which means it could not be removed from the array and the metadata header cannot be changed to remove the disk); no TRIM support, which is essential for the disk endurance and many more.

After the screenshots, you can see the part of the Linux dmesg command with the lines related to the HP HPSA Driver and how the system sees the disks.
The following screenshots start with a controller in hardware mode in (HPE terms – Smart Array Mode), then enable the HBA mode, the OS will see the disks as JBOD and then again enable the hardware mode (Smart Array Mode):

SCREENSHOT 1) Click on the controller “Smart Array P440” on the left and then “Enable HBA Mode” to enable JBOD mode.

main menu
Enable HBA Mode

Keep on reading!

Smart Array P440 – create multiple Logical Drives with different RAID Levels in one Array using Smart Storage Administrator

This article is to show you what different type of RAID logical drives and what strip size could be created on one Array consisted of multiple physical devices like hard drives or SSDs.
The following logical drives could be created or modified on Smart Array P440 with Smart Storage Administrator:

  • Multiple different RAID types with different strip sizes!!!
  • All RAID types could be modified and you could change the strip size to any type offered by the controller
  • Bigger RAID type logical drives could be change to smaller RAID type logical drives. Such as logical drives of RAID 5 type could be converted to RAID 0, RAID 1, RAID 6 with any strip size on-the-fly without losing your data. Read on to see all of the RAID type modifications you an make.

SCREENSHOT 1) Click on “Create Array” to create a new array.

main menu
Logical Drives

Keep on reading!