mdadm assembles AVAGO/LSI MegaRAID controller RAID 5 array

It is possible to read data with the software Linux raid using mdadm tool from a RAID 5 array created with the hardware raid controller AVAGO MegaRAID 9361-4i (LSI SAS3108).

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mdadm E sdb

Here, how a RAID 5 array with 3 hard drives and 1 SSD ( with CacheCade in write-through mode) is assembled by the mdadm and Linux software raid:

livecd ~ # cat /proc/mdstat 
Personalities : [raid0] [raid6] [raid5] [raid4] 
md125 : active raid0 sda[0]
      937164800 blocks super external:/md127/1 1024k chunks
md126 : active raid5 sdb[2] sdc[1] sdd[0]
      23436722176 blocks super external:/md127/0 level 5, 1024k chunk, algorithm 2 [3/3] [UUU]
      [==============>......]  resync = 72.0% (8438937704/11718361088) finish=336.8min speed=162234K/sec
md127 : inactive sdb[3](S) sda[2](S) sdd[1](S) sdc[0](S)
      2100568 blocks super external:ddf
unused devices: <none>

Note, it is essential that the CacheCade device is in write-through mode, which means the cache device is used only for reading and the data on the RAID array is consistent and written on it. The RAID 5 array was created here – AVAGO MegaRAID SAS-9361-4i with CacheCade – create a new virtual drive RAID5 with SSD caching. It seams possible for the data to be consistent if the CacheCade is write-back mode if there were few small writes and orderly shutdown prior to the removal of the AVAGO MegaRAID 9361-4i.
So, the above devices use proprietary LSI format, but here Linux software raid supports some of them:

  • md125 – the SSD device, which is a read cache only.
  • md126 – 3 hard drives in RAID 5 array.
  • md127 – logical device, which provides transparent interface to the

The important device is md126 and can be mounted under some live Linux CD/USB. Further, the md125 is a device, which has GPT partition table with 5 partitions:

livecd ~ # parted /dev/md126 --script print
Model: Linux Software RAID Array (md)
Disk /dev/md126: 24.0TB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system     Name                  Flags
 1      1049kB  211MB   210MB   fat16           EFI System Partition  boot, esp
 2      211MB   1285MB  1074MB  ext4                                  msftdata
 3      1285MB  23.9TB  23.9TB  ext4                                  msftdata
 4      23.9TB  24.0TB  53.7GB  ext4                                  msftdata
 5      24.0TB  24.0TB  16.8GB  linux-swap(v1)                        swap

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.

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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.

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Logical Drives

Keep on reading!

Smart Array P440 – create RAID 5 using Smart Storage Administrator

This article is to show how to create RAID 5 in Smart Array P440 hardware controller and what kind of migration is possible from RAID 5 on this controller.

Existing RAID 5 could be migrated to RAID 0 or RAID 5 (so the RAID Level transformation is possible) with different Stip size (any of the supported in the controller) on-the-fly with no data loss!

No data loss is available to the tested server HP ProLiant DL160 GEN9, check the manual for your generation.
You may check our more detail article on how to start HPE Smart Storage Administrator on your server here: Review of Smart Array P440 on a server HP ProLiant DL160 Gen9 using iLO – create, modify, delete array and view controller settings

There are the steps to create RAID 5 using Smart Storage Administrator:

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

main menu
Logical Devices

Keep on reading!