What is JBOD Mode? How Do I Enable JBOD Mode on Intel 12G SAS Adapters?

What Is JBOD Mode?

JBOD stands for "just a bunch of drives". JBOD mode passes through physical disks so that the operating system or host can see each individual drive. This is the opposite of a normal RAID controller, which groups physical disks together to form a single, often larger or fault tolerance, virtual drive.

JBOD mode is useful in some software storage solutions, such as Storage Spaces Direct, which require direct access to individual disk drives, rather than a RAID array.

Do All SAS Adapters Support JBOD Mode?

Not all adapters (HBAs) do, but many support it to a varying degree.

How Do I Enable JBOD Mode on Intel 12G SAS Adapters?

This involves changing the personality of a 12Gbit RAID adapters to turn off all RAID functionality and only enabling JBOD mode. The example below is from an Intel RMS3AC160 adapter but the instructions apply to most other RAID modules and RAID PCIe cards in the same series.

Note: Enabling JBOD personality mode will destroy and RAID volume on the disks. You should be able to move JBOD disks between JBOD personality adapters without data loss, but always make sure the HBA is in the right personality mode first, and ideally all adapters sharing disks should be at the same firmware level. In a new deployment, always deploy the latest HBA firmware before connecting the disks.



More Notes

Note: If you are using an Intel server platform that uses a motherboard such as the S2600WTTY or S2600WTTYR and cannot see or access the RAID BIOS options, first of all ensure that Quiet boot is turned off the main BIOS. If this does not help, ensure the BIOS is set for Legacy boot instead of UEFI boot. (Setup Menu > Boot Maintenance Manager > Advanced Boot Options > Boot Mode

Applies to:

Article ID: 680
Last updated: 13 Jun, 2017
Revision: 9
Stone Branded Products -> Servers and Workstations -> Frequently Asked Questions (FAQ) -> What is JBOD Mode? How Do I Enable JBOD Mode on Intel 12G SAS Adapters?