We have a Dell PowerEdge R730xd with 24 SSDs of 500GB each. We need to install Ubuntu 14.04 LTS on this machine, and use it as a database (postgresql).

Our RAID controller is an Avago MEGARAID, and to my knowledge it behaved exactly like a H310 card.

I set up 2 Virtual Drives in RAID10 (16 and 8), so we have now

  • /dev/sda (4TB)
  • /dev/sdb (2TB)

I'm having troubles installing Ubuntu 14.04 LTS. Even by choosing the most automatic installation (Guided: use entire disk /dev/sda) upon boot i get welcomed by the Grub rescue mode, with the message

attempt to read or write outside of disk 'hd0'

By executing some commands in grub rescue mode, I encountered these devices

  • (hd0,gpt3), unknown filesystem, should be the swap partition
  • (hd0,gpt2), recognized as ext2 partition, contains /boot folder, but trying to access that returns the same error (attempt to read or write outside of disk 'hd0')
  • (hd0,gpt1), recognized as unknown filesystem, it should be a BIOSgrub partition (we're in GPT mode after all)
  • (hd1), the 2TB drive

Trying to reinstall grub into /dev/sda using the Ubuntu LiveCD did not help. We're still welcomed by the same error. I could mount /dev/sda2 in rescue mode and check the content of grub.cfg, but i'm not really sure what needs to be checked. Everywhere it was correctly referencing (hd0,gpt2)

Even after running boot-repair we get welcomed by the same error:

  • First, I will just mirror the OS drive instead of putting them into a single RAID 10 strip. It is a bad idea to put OS swap on RAID strip. If allowed, I will dedicated a drive for database TEMP file processing. Second, did you check the RAID controller support for SSD TRIM ? – mootmoot Jan 3 '17 at 15:44
  • In addition, if your RAID controller are having a ridiculous low queue depth like PERC H310, you will going hit bottleneck, even with a top notch SSD serverfault.com/questions/769438/… – mootmoot Jan 3 '17 at 15:59

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