How to connect SAS hard drives to your PC

You can often find cheap SAS (Serial Attached SCSI) drives online, thanks to their use in enterprise environments, where drives need to be upgraded periodically for better reliability. However, one downside to buying them is their lack of compatibility with consumer hardware.

It’s easy to mistake these drives for more common SATA (Serial ATA) drives as they share the same form factor and has a nearly identical connector, except for four additional pins on SAS drives. This allows SATA drives to connect with the SAS interface.

Unfortunately, a SAS drive cannot connect to the existing SATA ports on your motherboard. So, your only option is passing them through a universal interface like PCI Express or PCIe, found on all modern motherboards.

PCIe is one of the fastest ways to connect peripherals to your PC. It’s commonly used for connecting graphics cards and high-speed NVMe storage devices that need multiple lanes of high-bandwidth connectivity.

HBAs and RAID controllers

The most common way of connecting drives via PCIe is through an HBA. RAID controllers are HBAs that feature support for hardware-accelerated RAID, which most general consumer systems do not need. Software RAID performs better and is easier to use.

Most OEMs like Dell, HP, and IBM often use RAID controllers that are just HBAs flashed with custom firmware. If you get hold of such a RAID controller, we recommend you flash it to IT mode. RAID controllers tend to work with only specific models of hard disks belonging to the same OEM and have restrictions on the maximum number of drives that can be attached.

Remember that support for IT mode flashing depends on the controller, so it’s best to get one that’s already been flashed. If you bought an unflashed controller, you could find guides online by searching your RAID controller’s model no. Some controllers don’t support this, so consult this list before purchasing one.

SAS Expanders and DAS

SAS expanders can help split a single connection from an HBA into multiple ports for connecting even more HDDs. A SAS expander like Intel’s RES2SV240NC lets you add up to 20 additional drives for adding more drives. We have an article covering what SAS Expanders are in detail if you wish to learn more.

You will also need SAS cables to connect drives from the HBA to SAS expanders. SAS Expanders can also function without a motherboard but need an HBA to communicate with.

Direct Attached Storage or DAS works similarly but is used for external storage of drives if your current PC is limited in space and dramatically reduces clutter by using much fewer cables. Drives are placed into caddies and slide into their respective slots without wiring up each drive individually.

Choosing the right hardware

Most hard disks have speeds of 6 or 12 Gbps, which can let you theoretically connect up to 42 of them to a full-sized PCIe Gen 4 slot on your motherboard. For comparison, a modern GPU like Nvidia’s flagship 3090 supports the same number of lanes, while a high-speed Gen 4 NVMe SSD takes four.

There are sufficient lanes on current-generation motherboards to connect multiple HDDs directly to your PC. However, costs will pile up if you want each HDD to have access to the maximum SAS bandwidth of 6 Gbps.

For reference, a new Gen 4 9500-16i HBA will set you back $833 at current market prices. Adding a suitable 12Gbps SAS expander to the mix will add another $355 to your budget. We recommend this setup if you need the highest bandwidth per drive and can afford the costs.

The older generation used HBAs like this LSI 9211-8i is a cheaper solution suitable for home or small business use. You will lose out on a per-drive bandwidth, especially when adding multiple HDDs due to the slower PCIe 2.0 interface, but considering most use their drives in some form of RAID, this is an excellent solution for adding SAS drives to your PC.

Art of Server’s YouTube video compares the various models of HBAs available on the market and is worth a watch before investing in an HBA:

In conclusion, if you’re getting a good deal on used or refurbished SAS drives, then buying an HBA and a SAS Expander should help you easily connect these drives to your PC.

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