Host Bus Adapters

Shop host bus adapters by type

Fibre Channel and SAS HBAs each have their own page: Fibre Channel HBAs for 8Gb to 32Gb SAN connections and SAS HBAs for 6Gb and 12Gb drive and enclosure connections. Fibre Channel HBAs take SFP+ optics, which sit under optical transceivers, and HBAs sold as storage-array spares are on storage array HBAs.

HBA, RAID controller or NIC

An HBA passes storage through to the operating system, a RAID controller builds and manages arrays itself, and a NIC carries network traffic:

Software-defined storage picks the HBA: Proxmox advises avoiding RAID controllers for Ceph and using an HBA instead. For hardware RAID, browse RAID controllers.

Fibre Channel speeds and controller series

Fibre Channel HBAs negotiate down to slower SAN links: Broadcom lists its Emulex LPe31000-series 16GFC HBAs as auto-negotiating 16, 8 or 4GFC, and its LPe32000-series 32GFC HBAs as auto-negotiating 32, 16 or 8GFC. The controller series by speed generation:

SAS HBAs

A SAS HBA attaches SAS and SATA devices to the server; an eight-port external 12Gb/s Broadcom HBA, for example, puts its lanes on two mini-SAS HD (SFF-8644) connectors and can address as many as 1,024 SAS or SATA devices. Dell and HPE sell SAS HBAs under their own HBA names, with internal or external ports. For how a JBOD differs from RAID, read What is JBOD?

Multipath: two HBAs, one array

Two HBAs give a server two independent paths to the same storage. Dell's best-practice guide for Microsoft MPIO with its SC Series arrays describes the purpose of multipath I/O as redundant paths, so that when one path goes down another keeps the storage connected, with load balancing across the active paths; it covers Fibre Channel and iSCSI SANs and SAS direct-attach connections, notes that MPIO can use up to 32 paths per device, and calls two to four paths common.

Host bus adapter questions

What is a host bus adapter?

A host bus adapter (HBA) is the expansion card that connects a server to storage. A Fibre Channel HBA links the server to a Fibre Channel SAN, and Broadcom rates its Emulex LPe32000-series cards to negotiate 32, 16 or 8GFC links automatically. A SAS HBA connects SAS and SATA drives and enclosures; an eight-port external 12Gb/s card from Broadcom, for one, carries up to 1,024 devices.

How does a host bus adapter differ from a RAID controller?

Who builds the array. An HBA passes each drive or LUN straight to the operating system, and Dell describes its 12Gb/s HBA-series cards as non-RAID adapters for drives, JBODs and tape. A RAID controller such as Dell's PERC 11 builds virtual disks itself, at RAID levels from 0 up to 60. Software storage such as Ceph wants the HBA, and Proxmox advises against RAID controllers there.

Can I use two HBAs for multipathing?

Yes, that is the usual design. Dell's MPIO best-practice guide describes multipath I/O as giving a server redundant paths to its storage, so a failed path does not interrupt access, with load balancing across active paths over Fibre Channel, iSCSI or SAS. Cable each HBA to a separate path to the array and enable the operating system's multipath feature; two to four paths per device is common.