User:BTullis (WMF)/RAID

How to configure Raid in the BIOS

Hosts with PERC H750 RAID Controllers

We have experienced a number of issues with the configuration of this RAID controller card, particularly when there are two different classes of disks installed.

Examples of these are the newer kafka-jumbo servers and the kafka-stretch servers in both eqiad and codfw.

This page of the Dell PERC 11 users guide says the following:

Virtual disks (VDs) are enumerated, second based on the virtual disk target ID.

Target IDs are assigned to the VDs in the descending order when they are created. The first created VD is assigned the highest available target ID, and the last created VD is assigned the lowest available target ID.

Therefore, the last created VD is discovered first by the operating system.

Select the boot device from the logical volumes available

Therefore, when creating multiple virtual disks, such as a RAID10 for data and a RAID1 for the operating system, we should always create the operating system volume last.

In addition to this we have to configure which of the two logical volumes is to be the boot drive. See the screenshot.

Even when doing this, sometimes the controller has thus far proven to be unpredictable in terms of saving this configuration.