I have a very old laptop that was state of the art when originally released, back when SSDs were starting to enter the consumer market. When I bought mine, it was advertised as a 500 GB SSD Ultrabook, but it was always too slow to actually be an SSD.

I've finally decided to open it to see if my atrocious network card could be replaced and it turns out there was an SSD all along! It's a 24 GB SSD drive most likely to be used for fast booting (which surprises me because the boot partition had never been there to begin with):

small, card like SSD

However, I don't know what this type of SSD is called. I would like to replace it but nowadays SSDs are longer than this one (which is about 5 x 2.5 cm) and the capacitors on the left prevent me from using them.

So is there a specific way to refer to these SSDs? Are they still being sold today?

Is it preferable to have a larger SSD in its place or should I simply remove this drive and aim to replace the HDD with a SATA SSD?

  • It is most likely a SATASSD (older SATA data bus)
    – John
    Commented Nov 27, 2021 at 15:40
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    You can replace it with a larger mSATA. This format was popular at the time but was gradually replaced by more modern drives with M.2 connectors. Commented Nov 27, 2021 at 15:42
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    "but it was always too slow to actually be a SSD." - SSDs aren't necessarily fast, especially old ones. I had an original Eee PC, which had an embedded 4G and 16G SSD. The 4G SSD was slow, and the 16G SSD was glacial.
    – marcelm
    Commented Nov 28, 2021 at 11:08
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    I have a very old laptop that was state of the art when originally released, back when SSDs were starting to enter the consumer market - Then it's not a very old laptop. This is a very old laptop: upload.wikimedia.org/wikipedia/commons/8/8d/Epson-hx-20.jpg Commented Nov 29, 2021 at 0:08
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    Did you or someone else replace the supplied OS with something else? Could be the person doing the install didn't realise there were several disks. I'd suspect the original OS was set up to use both disks better.
    – Criggie
    Commented Nov 29, 2021 at 0:11

4 Answers 4


Most likely this SSD is/was used as part of an ExpressCache setup. The idea is/was to offload certain caching operations of the HDD onto an SSD for speed. It may have been advertised as a "hybrid drive" or "solid-state cache" or similar. In my experience the benefit is rather marginal.

The SDD is probably only useful when running the proprietary caching software that came preinstalled on the machine. On my Y510p, this disk shows up in Windows as an OEM partition on Disk 0 in Disk Management and I can't, for example, format the volume to make it available to the filesystem for storage or as a boot partition. The software runs as "ExpressCache Service".

Replacing it with a higher capacity mSATA SSD might eke out some more performance if you can somehow make sure that the caching software recognizes it. I don't think you'll be able to use that slot to mount another storage device.* If you install a SATA SSD to replace the HDD, you might even consider disabling the caching software and removing this SSD, as there will be no benefit to having an SSD cache for an SSD.

*Edit: I searched around a bit and found a few stories (example) of successful use of the mSATA slot to mount a drive to be used for boot or storage. I would be careful, as this use was probably never tested or recommended by the manufacturer.

  • 1
    Also common at that time was "Intel Smart Response Technology" built on top of "Intel Rapid Storage Technology". Same cache concept. There are various instructions available for correctly reformatting a SSD (or portion thereof) to serve as a cache partition for a larger hard drive, followed by activating it in firmware (BIOS/UEFI) config. IME there is a significant benefit, especially during boot.
    – Bob
    Commented Nov 30, 2021 at 2:30

It's mSATA as seen here:

enter image description here

Usually the manufacturers device specification contains this kind of information.

24GB is not huge, replace it if you must, but I would look for a new laptop.

  • Thanks, they still seem to be around today. Unfortunately there was never any mention of them in the specs page. I'm dying to replace this notebook, but the semiconductors crisis forced me to survive with this rattletrap for another couple of years. Commented Nov 27, 2021 at 15:48
  • Hmmm, strange, Does the laptop actually see it? or has someone shoehorned it in place in the hope that it works, but doesn't?
    – Bib
    Commented Nov 27, 2021 at 15:50
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    You should be able to replace the current spinning rust with an ssd.
    – Bib
    Commented Nov 27, 2021 at 15:52
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    lsblk shows it as sdb, but the boot partition has always been on sda2. Ironically, it seems that all this time has passed and that SSD has never been used. Commented Nov 27, 2021 at 15:53
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    @manoelpqueiroz As described in Peter Schilling's answer, this was probably to be used as an SSD cache for the larger HDD, but required operating system support, which may have been available in Windows but not whatever flavour of Linux you are using (or would have required additional configuration you didn't do). You're probably better off replacing the original (larger) HDD with an SSD and forget about this one.
    – jcaron
    Commented Nov 28, 2021 at 22:34

it's mSATA, it might be faster and easier to google the part number (SMS151S3/24G) to get an answer for similar questions (that's how I found it and got this https://tech4drive.com/product/SMS151S3-24G) the laptop may not support a newer or bigger SSD, and it also may not be worth replacing anyway, there are likely other bottlenecks in your hardware, if you replace the regular 2.5" sata drive with a ssd it will be more likely compatible if you get a new computer

  • 2
    I think you are being overly pessimistic, by the time mSATA was introduced, SATA 6G was already out. So i'd think the chances of compatibility issues are slim.
    – plugwash
    Commented Nov 30, 2021 at 4:20
  • not if its used as for cashing the HDD in some circumstances Commented Nov 30, 2021 at 4:30
  • but you are right compatibility issues are slim Commented Nov 30, 2021 at 16:06

As others have pointed out it's a MSATA SSD.

MSATA uses the miniPCIe form factor but with the high speed signal lines used to carry SATA instead of PCI express. Some slots may support both PCIe and SATA.

The intent with the drive was almost certainly for it to be used as a "cache" drive. The drive would be used to store copies of frequently accessed data thus improving performance without the expense of a large SSD.

On Windows this would require third party software which was likely to have been bundled with the machine when new, but may well have been lost during a re-install. On Linux there seem to be two SSD caching implementations in the kernel, but I'm not aware of any distro setting one up out of the box.

I just took a quick look on Amazon UK looking for the cheapest drives from a brand I had heard of. In mSATA I found a Transcend 256GB drive for £34.60, an Integral 512GB one for £57.10 and an Integral 1TB one for £129.99; I couldn't find a 2TB one from a brand I recognised at all. Compare that to 2.5-inch SATA where I found a 256GB Patriot drive for £25.79, a 512GB Patriot for £44.99, a 1TB Crucial for £72.99 and a 2TB Crucial for £146.17.

In other words, for only slightly more than the cost of a mSATA drive you can get a 2.5 inch drive of double the capacity. Given that, is it worth buying the mSATA drive so you can keep a HDD in the mix? Only you know your use cases well enough to answer that.

Also when I look for mSATA SSDs the top tier brands like Intel, Crucial, WD, Samsung and Kioxia seem conspicuous by their absence other than what appear to be a handful of old-stock models. Perhaps I'm overly brand-loyal but I'd be reluctant to go mSATA for this reason.

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