Attaching LTO Tape drives via USB or Thunderbolt

TL;DR

If you don’t have a computer with PCIe expansion slots – there are no easy and inexpensive ways of attaching an LTO tape drive to it.

Introduction

For quite some time now I’ve been doing my backups (including all of the content on this website) by Tape. Why? Quite frankly I just like them. If like me you buy older generation drives second hand for personal backup, I find it actually works out cheaper than having say, two or three (or more) USB hard disks. The low cost of the media also allows me to have a history of my data (say, a copy from each year), because sometimes, things get lost or corrupted, I don’t realise it, then end up overwriting a good (backup) copy of data with bad (or no) data.

There are other significant benefits of tape – particularly in the robustness and simplicity of the media. Tape media is purely mechanical (aside from the RFID chip on the side) meaning that there’s no electronics which can be damaged. The physical spool of tape is also very robust, unlike the glass platters of a hard disk.

Dropped your tape and smashed it? Somehow managed to kill that RFID chip? No problem. Just buy another tape, undo the four Phillips screws on the bottom and transfer the tape spool to another shell, and you’re back in business. Good luck doing anything like that on a hard disk!

Happened to be subject to a massive electrical surge or lightning strike while your one and only copy of data on a tape was in the drive? Once again, no problem. Tapes have no electrical connection to the drive whatsoever, even during operation.

When talking about backup, IT administrators often use the term “air gap” meaning that data cannot be wiped out by a virus or other accidental software or power incidents. Tape, today, remains the undisputed the king of air gaps.

SFF-8088 SAS Connection on the rear of a tape drive

LTO Tape drives (these days) come with either Fiber Channel, or SAS interfaces – there are no other options. This makes them a little difficult to attached to (For example) a Mac, or any Laptop. Desktop PCs & Mac Pro’s are not an issue because you’ll likely have PCIe slots where a SAS or Fiber Channel host adapter can be installed.

I don’t actually have any PCs with PCIe slots in them anymore, and haven’t had for quite some time so have had to confront this issue myself.

Option 1: USB

Some time ago a product existed to convert USB to SAS:

They originally sold for around US $250 but likely due to the decline of SAS usage in general, do not appear appear to be made anymore. They can still be found for sale, for typically very high ($500+) prices. If you can get your hands one for a good price, this may work out, but don’t  count on being able to get another.

4x Internal SAS to SFF-8088 cable

Assuming you can obtain one of these rather exotic items, you would then need an internal SAS to SFF-8088 cable, bearing in mind that SFF-8088 carries 4 SAS lanes, you’d just connect your USB to SAS adapter to port 1 – which is what the tape drive will be internally connected to. This would be a workable setup – but a bit ugly.

Due to the obscene cost and obscurity – I would not recommend going down this path.

Option 2: Thunderbolt (buy one pre-made)

If you’re not technical and/or not on a budget, there are a few ready-made Thunderbolt drives. These internally contain a PCIe to SAS host adapter as I demonstrate below. Expect to pay a $2000-3000 premium for this convenience.

Option 3: Thunderbolt (pre-made  SAS adapter)

This will be a little cheaper than buying a pre-built drive but still a lot more expensive than the option below. You’ll have to source the appropriate SAS cable. More about that below.

Option 4: Thunderbolt (make your own)

This is a far more sensible (and cheaper) option. Because Thunderbolt carries PCIe we can use (For example) an eGPU enclosure to carry a PCIe SAS Host adapter.

LSI SAS9207-4i4e SAS Host Adapter

I personally use an LSI SAS9207-4i4e. The LSI SAS9207-8e (two external ports) would also be suitable, as would many others. I have chosen this because it is a fairly recent adapter, which also has the very same SFF-8088 connector found on the tape drive. I got this adapter off eBay for $30.

The full setup

To the left we have a PCIe Thunderbolt enclosure containing the Host Adapter. There are lots of Thunderbolt PCIe enclosures on the market, you can pretty much just pick the cheapest one as a SAS Host Adapter is not a very demanding card to install in one. Single slot enclosures seems to be the cheapest at around $200 at the time of writing.

To the right is the tape drive.

If we go down this path, in addition to only having spent $300 (excluding the cost of the drive), we also have the bonus of having a few new items that have other uses. For one the Thunderbolt enclosure can be used for other PCIe cards, also the SAS Host Adapter can be used as a very high performance connection for SATA hard disks too. There are many different cables and enclosures which can make use of this.

SAS cable selection

SFF-8088 cables come either x1 (one lane) or x4 (four lane) variants. A tape drive only has one lane so either an x1 or x4 cable will be OK. x1 cables are considerably thinner and lighter than x4 cables.

You can also buy fairly long SAS cables too. Bear in mind that tape drives are quite noisy, you may want to consider buying a longer cable (up to 10M / 33ft) so you can put the drive somewhere it’s not going to irritate you.

Left: SFF-8644 connector. Right: SFF-8088 connector

There are multiple type of external SAS connector presently in use and these days SFF-8644 is beginning to replace SFF-8088 despite it still being common on tape drives. It’s not a problem if you end up having to buy a SAS Host Adapter which has a SFF-8644 connector on it, you’ll just have to buy a cable which has the appropriate connectors on each end.

Operating system drivers

On Windows 10 I did not have to install any drivers for the Thunderbolt enclosure or SAS Adapter – it all just worked.

The only driver I did have to install was for the tape drive its self.

I have not yet tested my setup on Mac.

Hot plugging

I found that it all works like a charm. You can either hot plug the whole setup through the Thunderbolt cable, or you can just disconnect the SAS cable (or even power off the drive), as SAS is also hot-pluggable, if for example you use your SAS host adapter and PCIe enclosure for other things (as I do).

Fiber Channel instead of SAS

You could also substitute a PCIe SAS adapter for a Fiber Channel host adapter in your Thunderbolt enclosure if that’s the kind of drive you happen to have. You can do your own research on that. This is going to be a lot more complicated but the advantage of this option is that you could have your tape drive a very long way from your PC.

Are SATA adapters of any use?

For the most part, no. If you are starting with a SATA/eSATA controller, there is no way to adapt to SAS. You must start with a SAS controller. SAS controllers however, support either.

For the benefit of skim readers, and/or the impatient, here is the previous sentence spelled out unequivocally

There are some scenarios where SATA to SAS/SFF adapters are useful – for example:

Let’s say you have a SAS controller with a bunch of SATA HDDs attached via a SAS to SATA octopus cable, and you happened to have a spare port – it is possible to adapt that port back to SAS, to attach to a SAS tape drive.

Essentially – it doesn’t matter if intermediate the cabling or connectors are SATA, just so long as you have SAS hardware at either end. SAS and SATA cables & connectors are eletrically the same i.e. 2x 100Ω differential pairs each – differing only mechanically.

It also doesn’t matter that you are using a mix of devices on one host adapter – so long as you’re not trying to put those devices into a single RAID volume – SAS controllers don’t care.

Because the tape drive will only be using one port on the SFF-8088 connector, you can connect that one spare SAS port to port 1 on the adapter.

Older laptops with ExpressCard slots

There are some products which adapt ExpressCard to PCIe which would allow a SAS adapter to be attached.

There are some examples of SAS ExpressCard adapters:

Sonnet 4-Port Tempo SAS Pro ExpressCard/34

Very few true SAS ExpressCard adapters like the above were ever made. None are made anymore and anyone who has one may expect a high price for it.

Most products resembling the above are 4x SATA controllers with an SFF-8088 connectors, which is of no use for tape drives.