SSD for Mini PCIe slots (WWAN not mSATA)

So I have a few older laptops that have free mini PCIe slots, typically intended for WWAN cards. Typically, these slots do NOT have lines run to the laptop's SATA controller, and thus you just can't pop a typical mSATA card in. Are there any mini PCIe SSDs out there with an *onboard* SATA controller that can be used in one of these slots? I realize booting with one of these may be a problem, but I can always use the extra storage.

My research also indicates that WWAN slots may only have USB lines run to them. Is this true?

 

True mini PCIe ssd cards do exist, but are rare, have tiny capacities and command a hefty price. Finding the real McCoy is also exceedingly difficult since tons of sellers list mSATA cards as 'mPCIe'.

Much better is to use an adapter, either to SD or USB (say, for an internal port). Speed on these sockets cards is limited to 100MB/s, so look for the highest storage space you find at such a range. A nice combination: an MR04 MiniCard adapter + SanDisk Extreme PRO UHS-I (up to 512GB). UHS-II and over is wasted because the port lacks the extra pins these cards require to run at their full speed, simply defaulting back to UHS-I.

Yes, the communication protocol is PCIe and/or USB. You need to know the specific protocol before ordering an adapter (the MR04 is USB-type). There's a PCIe variety too (MR04R), but its $125 price-tag might sway the balance against this option.

Whether or not the slot is bootable depends on the system's bios and it being USB-type. Chances are very slim it can be booted from and also remember that 100MB/s limit; a decent, regular hdd will outperform any ssd run from that socket.

 

Actually, I've found that booting an SSD in a USB 2.0 enclosure performs surprisingly well given the ~30MB/sec throughput. Latency plays an important role in overall responsiveness and program load times. I am confused about your statement of 100MB/sec throughput; the MR04 seems to be a USB 2.0 device, which means around 30MB/sec effective throughput. Do you mean that the MR04R maxes out at 100MB/sec?

But it's still an excellent suggestion that I never would have thought of. And one of my laptops does have the ability to boot off of it's native SD slot, so perhaps the BIOS could handle booting from this device as well.

I've also heard that it's not a good idea to boot from an SD card, but I'd like that option in a pinch. Are there "high endurance" SD cards that would be better suited to that purpose?

 

That makes sense; no spin-up, after all.

The slot card itself is 100MB/s, the MR04 simply puts on a further limit, but there might exist other adapters that will not add such a cap. The MR04R is 25MB/s, but it is unlikely you actually require an adapter with PCIe interface. Most manufacturers opted for the faster and ubiquitous USB option.

Yes, that is because, like all flash types, they suffer from voltage drift. So without refreshing static data periodically (say, once a year) it can become corrupted. Most newer cards are also TLC, which have about 1/10th to 1/100th the write endurance of older SLC, further compromising data-integrity when used as a boot device or portable office-to-go. Error correction can compensate for that to some extent and so can embedded rewrite algorithms, but then you'd have to dig deep into the specifications of these cards (look for terms such as ECC, BCH, LDPC, 'refresh' and 'wear leveling'). Anything labeled Industrial, Enterprise, Pro and being a fair bit more expensive $/GB-wise may be suitable. So SLC plus error correction would make for the safest choice, but at the expense of maximum available size; 8GB is usually the ceiling. If that is sufficient then SLC is great, otherwise look for premium MLC/TLS cards. If these are too expensive; being so small you might also simply schedule writing periodic images and keep a second, backup card at hand.

ps.
Be aware that all SSDs have SLC cells inside them, these being used for its own cache and firmware. After all; if the index fails then so will the entire drive. Manufacturers have a tendency to murky the waters by claiming their product has 'SLC-technology' or such, which, while technically true, only applies to the drive's cache and fw, whereas the bulk of its cells are MLC/TLC.

 

Edit: There may be a fly in the ointment. I know the WLAN adapter is BIOS whitelisted, so I suppose the WWAN slot could be whitelisted too. Would any unapproved PCIe cards be blocked, or just non-standard WWAN cards?

Thanks for all the great info about flash endurance.

I'm still puzzled about the mini PCIe bandwidth. In researching eGPUs, a common solution is to use a mini PCIe slot as an interface to the GPU because it features full PCIe x1 bandwidth (2.5 Gbps to 8 Gbps, depending on generation.) Is the 100Mbps limit because it's a WWAN slot? Assuming it's not USB, of course.

 

@imrazor modules WWAN are all USB. If MiniPCIe slot has both USB and MiniPCIe wired and intended for WWAN, usually only the USB part is whitelisted.

 

Ah, sorry. That was inaccurate on my part; the 100 MB/s (800 Mbps) limit is for the card, not the slot. If you manage to find an adapter with a higher ceiling then please report back.