I always use IBM or HGST and Hitachi 72,000rpm , 2.5” IDE drives in old laptops.
They seem to work great. And have way better performance then the original hard drives and run quiet and cool.

Personally I'd try my luck with an m.2-IDE adaptor in 2.5 inch form factor plus an m.2 SATA SSD instead of using old laptop HDDs that may have been knocked around a fair bit.

I know this doesn't answer your original question but since you mentioned only prices kept you away from 2.5 inch SSDs I hope this helps anyway.

Another option is an mSATA SSD. They're quite cheap, so long as you don't mind purchasing from China, with capacities starting from 32GB up to 2TB. You'd just need an mSATA to IDE 44-pin adapter and they should be small enough to fit into the HDD compartment of most laptops.

mSATA SSD drives obviously aren't as fast as regular SATA SSDs or M.2 drives, but used on IDE they'll certainly outperform an old regular 2.5" HDD.

mSATA is simply SATA on a different connector. Same with m.2 SATA. There's no speed differece. By now m.2 SATA drives are simply easier to come by imho so that's the form factor I suggested.
m.2 also allows for PCIe SSDs but those don't work in IDE-m.2 adaptors since those only feature a PATA-SATA bridge chip and obviously no PCIe lanes.😅

By the way, I don't mind the slowness of old hard drives.

I know that mSata SSDs are obviously faster, however I just want to buy a hard drive to use for experimental purposes
(I already have a 100gb Seagate Drive in my main old laptop, my MD 9783, which is running Windows 98 SE and XP Home SP3 in dual boot).
I want to buy a 2nd hard drive so that I can play around with different operating systems without having to delete everything on my main drive.

Personally, I don't think that an mSata adapter and an mSata SSD are worth buying for around 30 bucks if I'm just going to use it for experimental uses.

I just don't know from which HDD brand to buy. (Toshiba, Fujitsu, Seagate, WE, etc)

I've seen lots of Toshiba and Fujitsu HDDs fail, so I won't recommend them.

I must say that those HDDs were installed on Canon copiers, so maybe those fails were related to vibrations and/or temperature... but still I avoid buying HDDs of that brands. On the other hand, those HDDs were replaced with Samsung ones (40Gb) and I don't remember any of those drives failing.

Zup wrote on 2020-08-15, 11:17:

I've seen lots of Toshiba and Fujitsu HDDs fail, so I won't recommend them.

Especially those Toshiba GAS/GAX series with fluid bearings that inevitably seize solid after a few years.

As for SSD, many of those noname 2.5" SATA SSDs have a board that's often shorter than the enclosure (ofter just half the size), so you can gut one of those, couple it with a 44 pin to sata bridge (using a reputable chipset, so Marvell* or JMicron) and still fit inside the laptop.

* Early WD SATA drives were nothing but a regular IDE drive with a Marvell IDE-to-SATA chip integrated onboard, to me that should mean that they are a reliable enough solution.

andrea wrote on 2020-08-15, 13:19:

Especially those Toshiba GAS/GAX series with fluid bearings that inevitably seize solid after a few years. […]
Show full quote

Zup wrote on 2020-08-15, 11:17:

I've seen lots of Toshiba and Fujitsu HDDs fail, so I won't recommend them.

Especially those Toshiba GAS/GAX series with fluid bearings that inevitably seize solid after a few years.

As for SSD, many of those noname 2.5" SATA SSDs have a board that's often shorter than the enclosure (ofter just half the size), so you can gut one of those, couple it with a 44 pin to sata bridge (using a reputable chipset, so Marvell* or JMicron) and still fit inside the laptop.

* Early WD SATA drives were nothing but a regular IDE drive with a Marvell IDE-to-SATA chip integrated onboard, to me that should mean that they are a reliable enough solution.

+1 for IDE to SATA adapters . I use SinLoon brand ones with a Jmicron chipset .
+1 To using an SSD, though I personally would not touch the no-name ones. Branded ones from compagnies that actually have a reputation and a web presence are really inexpensive anyway and probably quite small too if looking at small capacity ones .

CF to IDE or SSD to IDE /Thread. But seriously anything except travel star aka death star.

Intel486dx33 wrote on 2020-08-15, 09:05:

I always use IBM or HGST and Hitachi 72,000rpm , 2.5” IDE drives in old laptops.

That has got to be the fastest spinning disk that I have ever heard of. 😉 At those speeds, I'd expect a space-time rift to open up, allowing it to retrieve data from the past. I always joked that if time travel became a thing, someone would need to invent a temporal cache, that would do that very thing, 🤣.

This one works well.

Thallanor wrote on 2020-08-17, 15:59:

Intel486dx33 wrote on 2020-08-15, 09:05:

I always use IBM or HGST and Hitachi 72,000rpm , 2.5” IDE drives in old laptops.

That has got to be the fastest spinning disk that I have ever heard of. 😉 At those speeds, I'd expect a space-time rift to open up, allowing it to retrieve data from the past. I always joked that if time travel became a thing, someone would need to invent a temporal cache, that would do that very thing, 🤣.

Let's see how long it takes Intel486dx33 to realize you're joking about the fact that he typoed the number of digits in his drive RPMs... 😉

Stiletto wrote on 2020-08-17, 19:17:

Thallanor wrote on 2020-08-17, 15:59:

Intel486dx33 wrote on 2020-08-15, 09:05:

I always use IBM or HGST and Hitachi 72,000rpm , 2.5” IDE drives in old laptops.

That has got to be the fastest spinning disk that I have ever heard of. 😉 At those speeds, I'd expect a space-time rift to open up, allowing it to retrieve data from the past. I always joked that if time travel became a thing, someone would need to invent a temporal cache, that would do that very thing, 🤣.

Let's see how long it takes Intel486dx33 to realize you're joking about the fact that he typoed the number of digits in his drive RPMs... 😉

The kicker..... iPads use a 72,000 rpm drive instead of solid state storage. That is why an iPad is the best thing ever made ever.

The title of this post reads “Most reliable 2.5 hard drives”.
Not SSD’s.

Intel486dx33 wrote on 2020-08-17, 20:25:

The title of this post reads “Most reliable 2.5 hard drives”.
Not SSD’s.

But the OP's first post does mention  IDE SSDs .

I have Toshiba, IBM and WD 2.5'' HDDs and all of them are still working to this day. I don't think the brand is really important unless you get a known problematic model (such as the 3.5'' Deskstars), just try to focus on getting drives that are either new or with a low amount of power-on hours. Some sellers may be able to tell you something about the past history of the drives, and you can also get some details if SMART is supported.

I've never had a drive fail myself (although I have failed drives).

But anyway, Samsung built the fastest 2.5" ATA drives. You have the single platter HM160HC. Or if you want to stay below the barrier, the similar HM080GC could do the trick.

Most reliable, damned if I know, but ones released later tend to be built better. I ordered one of those and the build date is on the disk, some time in 2009. Pretty much the end of the ATA period.

By the way, the drive makes an annoying clicking noise (SLAP!) occasionally. Seems to have no effect on usage or data quality.

Intel486dx33 wrote on 2020-08-17, 20:25:

The title of this post reads “Most reliable 2.5 hard drives”.
Not SSD’s.

But a (gutted) SSD is the only way you can fit a modern commodity (therefore cheap) storage unit plus a SATA adapter in the footprint of a regular 2.5 drive.

Intel486dx33 wrote on 2020-08-17, 20:25:

The title of this post reads “Most reliable 2.5 hard drives”.
Not SSD’s.

Not to yank your shit around, but SSD are harddrives. SATA are also IDE, just a really modern and advanced version.

What you were thinking about, is that SSD are not spinning platter drives. Harddrive is just that internal storage device that are not removeable, as for example in a floppy disk drive or zip drive.

Also. SSD are just a storage technology. You can take an CF-to-PATA adaptor, jam in an SD-to-CF adaptor with an SD card. And you have an SSD solution for your old 486 computer. And it is also an IDE harddrive as well. SSD does not exclusive mean that modern 2.5 inch SATA drive, that was beginning to get populair some 10 years ago.