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We have HP DL360e G8 with B120i RAID controller (which is FakeRAID) and i have configured RAID 1 in RAID configuration utility. After CentOS 7 installation when i run fdisk -l i am seeing two individual disk with same partition size.

I should suppose to see single disk (/dev/sda) right? 

Disk /dev/sda: 500.1 GB, 500107862016 bytes, 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: dos
Disk identifier: 0x00020b93

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      526335      262144   83  Linux
/dev/sda2          526336     8914943     4194304   82  Linux swap / Solaris
/dev/sda3         8914944   976707583   483896320   8e  Linux LVM

Disk /dev/sdb: 500.1 GB, 500107862016 bytes, 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: dos
Disk identifier: 0x00020b93

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *        2048      526335      262144   83  Linux
/dev/sdb2          526336     8914943     4194304   82  Linux swap / Solaris
/dev/sdb3         8914944   976707583   483896320   8e  Linux LVM
Vlastimil Burián
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Satish
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1 Answers1

2

Your assumption of seeing a single drive is correct.

That said, I have my own bad experience with FakeRAID (BIOS-assisted RAID).

It just does not work well with most of Linux distributions.

My recommendation is to:

  1. Disable FakeRAID in BIOS

  2. Install mdadm

  3. Set up a very manageable and reliable software RAID

I sadly don't know, why you are seeing two drives instead of one.

Performance-wise mdadm is the same CPU workload. There is absolutely no difference, guaranteed.

For information about Bootable RAID using mdadm, please refer to one of the articles that suites you best.

Vlastimil Burián
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  • But i have few more server running `B320i RAID Controller` and they seems working fine and showing single drive in CentOS 7.3. so why B120i having issue? – Satish Jun 28 '17 at 05:49
  • I totally agreed with you, I am only worried about performance between `B120i` Vs `mdadm` – Satish Jun 28 '17 at 05:54
  • Does `mdadm` provide boot level protection? just trying to find what is the difference between `rakeRAID` and OS Raid? – Satish Jun 28 '17 at 05:57
  • @Satish You want to use this RAID as a boot drive? That is a little complicated. – Vlastimil Burián Jun 28 '17 at 05:59
  • I want full redendency not just single file system protection, i want my OS up and running 99.999 uptime. – Satish Jun 28 '17 at 06:02
  • I understand, in my case we have no data all we have CPU crunching and availability of OS, can't we RAID /boot partition? – Satish Jun 28 '17 at 06:06
  • In my question if i am seeing two disk in `fdisk -l` that mean my `B120i` RAID is broken right? – Satish Jun 28 '17 at 06:11
  • @Satish I believe so. But since I am no longer working with FakeRAID for years, can't be sure. But the probability is high enough. – Vlastimil Burián Jun 28 '17 at 06:13
  • no worry! Thanks and thus i accepted your answer – Satish Jun 28 '17 at 06:13
  • @Satish You are welcome, friend. – Vlastimil Burián Jun 28 '17 at 06:14
  • @Satish, there are plenty of how-tos on the internet explaining how to setup a redundant `/boot` partition with `mdadm`. The only difference here is that you will map `/dev/sda1` and `/dev/sdb1` to `/dev/md0` and the caveat here is that you will have to install grub on both partitions ( `(hd0,0)` and `(hd1,0)` on grub sintax to -> `sda1` , `sdb1` ) to have a redundant bootloader, but the grub config file will point to `/dev/md0` as boot partition ( `set root='(md/0)'` ) - https://www.howtoforge.com/how-to-set-up-software-raid1-on-a-running-system-incl-grub2-configuration-debian-squeeze-p2 –  Jun 28 '17 at 12:51