[ Updated Dec. 19, 2025, covering connectivity and read/write speeds and Dec. 22, with info on supply lines. ]
Recently, I wrote about the gear I use to backup my data (link) and, in it, I mentioned a relatively new Blu-ray Disc technology that stores up to 100 GB on a single, write-once drive at a very affordable price. Even better, this unit supports M-DISC, which offers storage that lasts for hundreds of years and can’t be modified once written.
Intrigued to learn more, I contacted Larry O’Connor, CEO of OWC.
Larry: What is the OWC Mercury Pro?
Larry O’Connor: The OWC Mercury Pro is our plug-and-play external optical drive enclosure. It works with almost any modern or older Mac or PC and it lets you use high-capacity Blu-ray media, including quad-layer discs and M-DISC – for simple and dependable long-term storage. It supports Mac, Windows and some Linux systems.
Larry: What storage capacities does it offer?
Larry O’Connor: That depends on the optical drive you install, but – for example – a quad-layer Blu-ray disc gives you up to 100 GB per disc and M-DISC media is available in Blu-ray formats as well. It is a huge step up from the 4 to 8 GB limit of DVD.
NOTE: On the OWC website, you need to choose the 16X Blu-ray Disc option (see screen shot at right) to get this capability. (Retail price: $179.99 US.)
Larry: Optical media has been in decline for several years. Is this technology still supported on Mac and Windows? Do we need any special drivers?
Larry O’Connor: Support is built into macOS and Windows. Linux compatibility depends on the distribution and installed optical drive Mercury Pro works through standard USB and uses standard SATA optical drives, so there are no special drivers or workarounds. You plug it in and the system recognizes it right away.
Larry Jordan Notes: The 100 gigabyte disc capacity requires a BD-XL Blu-ray writer to engrave successfully. Several companies make them, OWC uses a burner made by LG.
Larry O’Connor: The OWC Mercury Pro connects via USB 3.0 (USB 3.2 Gen 1) using a Standard-A to Standard-B cable. The enclosure bridges USB to a standard SATA optical drive, which means it works plug-and-play with macOS and Windows systems and does not require proprietary drivers. While USB 3.0 offers up to 5 Gb/s of bandwidth, real-world performance is governed by optical media speeds rather than the USB interface itself.
Larry: I’m most interested in the Quad Layer drive. What data transfer rates can we expect? In other words, how long does it take to burn 100 GB of M-disk media and how fast can we read from it?
Larry O’Connor: Here are the specs.
Write (Burn) Speeds
Read Speeds
Larry: How does “quad layering” in Blu-ray Disc burning work?
Larry O’Connor: A quad-layer disc stacks four data layers inside the same physical Blu-ray. The drive writes and reads through each layer independently, giving you up to 100 GB on a single disc without changing the workflow. The process is entirely managed by the burner and the burning software, so the user experience stays simple.
Larry: What are M-DISCs?
Larry O’Connor: M-DISC is a type of optical media. It uses an inorganic, stone-like data layer instead of the organic dyes used in DVD and Blu-ray. Your burner literally engraves the data into that layer. This makes it highly resistant to heat, humidity, light, and data rot. The M-Disc (millennium disc) technology is designed literally to namesake seeking 1000 years, a millennium of reliable data storage/retrievability.
Larry: Are they truly likely to last for more than 100 years? How are these longevity limits determined?
Larry O’Connor: The lifespan comes from accelerated aging tests that simulate decades of exposure to heat, light, and humidity. And, because the data is etched into a stable inorganic layer instead of dye, it does not fade the way conventional discs do. Nothing is perfect… but the longevity advantage is very real and well-documented. One hundred years is at only one tenth of the design life… and should be more than realistic.
Larry: How many companies manufacture M-disks; in other words, if the company now making them decides to leave the market, are we out of luck?
Larry O’Connor: Only a handful of manufacturers produce true M-DISC certified media, right now. The important thing is, even so, that the discs you burn today stay readable in any standard Blu-ray drive in the future because the format itself is not proprietary. Your M-DISC archive remains accessible, as long as Blu-ray drives exist.
Larry: What software do we need to burn these discs?
Larry O’Connor: On Mac, Blu-ray burning typically requires third-party software such as Roxio Toast 20 Pro or other Blu-ray authoring applications – although even MacOS Finder has some limited ‘burn’ write capability directly. On Windows, you can use built-in tools or third-party software – i.e., Nero, ImgBurn, or any utility that supports Blu-ray burning. Nothing special is required for M-DISC. M-DISC is a media specification and hardware capability that work together without any special software settings or end-user process.
Larry: Are there recommended disc vendors?
Larry O’Connor: We always suggest choosing reputable brands for archival work. Verbatim is a common choice for M-DISC media and many creators also stick with well known Blu-ray manufacturers who publish their quality and testing standards.
Larry: What do media creators need to know when considering OWC Mercury Pro and M-disks for long-term asset archiving?
Larry O’Connor: They should know this is a simple and affordable way to create a stable, air-gapped backup that malware and ransomware cannot touch. A 100 GB optical disc gives you a fixed version of a project you can trust for decades, and the media offers long-term archival stability. For anyone who values long-term protection of finished work, this is an easy tool to add to enhance the workflow and a smart safeguard for the future.
Larry: I guess my most important question is: Is this high-density optical storage the tail-end of a dying technology or something we can count on going into the future?
Larry O’Connor: High-density optical has a solid future, but it should be seen as an enhancement to a smart archive strategy rather than the only pillar. It gives you a stable, permanent, air-gapped copy of your work, which is incredibly valuable, yet no creator should ever rely on a single medium to protect what matters. The safest approach is always a mix of storage types so your work is preserved even if one layer of protection fails. Optical plays an important role in that mix because of its longevity, cost-effectiveness, and simplicity, and it does that job very well.
Larry: Larry, thanks for your time.
FINDING THE HARDWARE
There is some confusion as to whether OWC is still selling the Mercury Pro because two OWC pre-sales support staff told me they were out of stock. I contacted Larry O’Connor about this specifically and he said: “Supply right now is very finite – but we have a quantity of units that will restore availability again within 10 days or less.”
However, he cautioned that while the future of Blu-ray readers for these discs is good, he has concerns about long-term availability of the burners. All current burners use LG drives. M-Discs from Verbatim seem to be readily available.
Current hardware choices:
10 Responses to How to Protect Your Data for Hundreds of Years
Hi Larry, you say that it is a write once drive. Does this mean you can only write to the disc once and it is no longer available for additional data?
Thanks for all your articles, Best Christmas and New Year wishes, Randal in England.
Randal:
By “write-once” I mean that once data is written to a section of the disc, more data can not be rewritten to the same portion. As to whether we can do add-on recording to black sections of the disc – what DVDs called “multi-session recording,” I will need to find out.
Larry
Hi, Larry –
I have been using M Disks for several years, and have had very good experience with Roxio Toast and the LG Slim burners on my iMac Pro and MacBook Pro M4 Max. I keep all of our “keeper” content on them, and usually make 2 copies. You mention 128GB capacity M Disks — is this something on the horizon? The largest I have been able to research have 100GB capacity.
Wishing you a very Merry Christmas and a healthy and engaging new year!
Jan
Jan:
I suspect the 128 GB is more my own hopeful imagining. I’ll correct my article. Thanks for telling me about your experience with this technology.
Larry
Did you find out if a larger file (for example, 250GB) can span over more than one disc? In this example, it would be three discs: the first with 100GB, a second with an additional 100GB, and a third partially filled with 50GB.
Thanks,
Larry Kerr
Larry:
Smile… I didn’t know I was supposed to look.
This all depends upon what Toast supports, not M-disc. The Toast website is very light on technical information. Still, let me see if I can find out.
Larry
Larry:
I contacted Roxio Toast support to ask about three things: Multi-session burning, disc spanning and how long it takes to burn a disc. Here’s what they told me:
Multi-Session Burning:
macOS does not support multi-session burns for DVDs or Blu-ray discs like BD-XL. This is not a limitation of Toast 20 specifically, but rather macOS itself, which prevents adding data incrementally to the same disc after the initial burn session.
Disc Spanning:
Toast 20 fully supports spanning large files or data sets across multiple discs. For more detailed instructions, please refer to the official user guide section on Data Discs: https://help.corel.com/toast/v20/en/official-help/index.html#page/toast%2Fdata-discs.05.11.html
Burn Time Estimate:
While we have not tested and noted an exact time, real-world burns of 10 GB to a 4X BD-XL drive average 20-30 minutes.
Larry
Thank you Larry. Very helpful information.
While long lasting is great, unfortunately with many terabytes to backup, this is not that helpful. But perhaps a good thing to start with.
Dennis:
TBs of media is outside the capacity of this technology. But there are many business and project files that are perfect for this. Think of a calamitous malware attack or hard drive collapse. What critical application, email, and business files need to be restored just to get back in business?
A couple of months ago I met with Tom Coughlin, former president of the IEEE, and we got to discussing optical storage. He showed me a “chip” about the size of a postage stamp, that held a terabyte of media. So, greater capacity is already available in the labs. The question is when does this emerge into the world…?
Larry