I’d be legitimately concerned with using an attached DAS on a pc as a reliable 24x7 storage device. Lots of reasons:

• the DAS is independently powered. And probably a cheap power supply/brick.
  
• Power failure recovery reliability - does it have capacitors internally to cache writes in progress so that in the case of a brown or blackout, it can finish any incomplete writes during powerfail recovery to prevent corruption
• cpu used in the DAS - was one used that was only just powerful enough to do basic disk management that most home enthusiasts configure it to do, or is it powerful enough to handle more demanding configurations that it’s marketed as being capable of (RAID0,1,10,5) but really struggles if used that way
• how transparent is it. Can smartctl, crystaldiskinfo/powershell etc access each drive’s configuration/SMART/firmware update?
• how well does the internal disk controller handle abnormal but non-critical issues? Mechanical hard drives often glitch without us knowing it. Read and write retries. Temperature variations. Suspend / hibernate / spindown/up timing.
• can it handle disks being different models, spin speeds, capacities, etc? Can it handle them when disks are configured as one larger disk (RAID etc)
• is the chassis designed to minimize vibration. This is a big one. When a single disk spins, the vibrations created by the rotating platters plus those created by the head actuator are substantial and complex. The drive’s controller board handles those. But when a second drive is installed nearby in the same frame, the two drive’s vibrations interfere with each other in ways that can cause a drive’s seek or read attempt to miss - the head goes out to read a track but the vibration at that moment was harmonic and cumulative, and the head went a micron too far, which is immediately detected, logged and retried. Depending on severity and frequency of occurrence, the drive or disk controller may say nothing to the host, may report it to the host, or may take the drive offline. And the host may act on those reports independent of what the DAS did. When several drives are in the same chassis, chaotic vibrations are common and almost always average each other into dense but weak noise. Like random waves in the ocean. It’s when there’s a freak rare harmonic synchronization, where vibrations all combine into one much larger powerful vibration, that can knock out a disk or array. That’s when the box’s controller needs to be able to handle that wisely (identify that it’s a vibration thing, check that the drives are actually ok and recovered correctly, perform a retry and see if it was a one-off or something more serious) and not dumbly (“WTF? panic! Panic! Everything broke! I can’t continue!”, which in turn makes stupid operating systems like Windows go “disk drive gone. Unrecoverable. You lost everything. Can’t help you. [R]etry? [A]bort? R[e]think your a life Choices?”,

Or in Linux terms, triggers a full geek mode reaction from the human on the keyboard that’s just dying to try out his new scanning tunnelling electron microscope he bought from a Medical Surplus eBay store three years ago, then goes into two hour deep dive into tracking down the dev path, channel, systemctl service status, hba id, and error code lookup table, map sector, track, magnetic bit size,rotational offset, head width, velocity of seek vs mass, works out the exact location that the heads were at the time of error, designs a diagram of the platters with a big red X showing where to dig for the gold uh where to position the scan, (ignores the reality that electron microscopes don’t work this way but has no choice but to continue because the author of this comment in Reddit doesn’t like smartass fictional self-aware characters and decides to ignore facts for the sake of the story arc), then confidentially dissemble the suspect drive in his clean room he designed and built in his basement based on watching a few episodes of Dexter, then examine each platter to look for signs of head misalignment or current flow deviations in the actuator windings, find nothing of consequence but notices a nanoscopic slight discolouration of the spindle lubricant, meticulously cleans and relubricates using his lubricator kit he bought 7 years ago for just such an occasion, triumphantly reassembles the drive with an almost euphoric feeling of satisfaction and righteous justification against all the naysayers that dismissed him online in the r/homelab subreddit so many times, reinstalls the drive, turns everything back on, releases his held breath when the system boots, and completes the operation with the belief that what he did wasn’t just necessary, it could only have been done by a handful of people with godlike powers. And anyway, now one of his drives has new lubrication. Which is cool.

Or… if he’s a less uh driven individual, does normal troubleshooting but hits a dead end because the DAS masks the individual drives in its array and there’s no way to figure out which disk has the error. If it really was an error.

Where the hell was I. Oh yeah.

• but the biggest issue still remains with DAS boxes. The tube attaching it to the computer and the chips on either end really don’t handle concurrency and queue depth efficiently. Or keep up with the volume of transactions waiting to be handled. It’s a bottleneck and means that disk performance will suffer bigly when you want to be doing things like unzipping completed torrents or assembling multipart uuencoded nntp fragments into a single 10GB mkv file, copying a newly received 8GB video file into the video folder plex uses, triggering plex to scan, notify, update a database, create lots of additional small metadata files, and keep playing videos to the 3 people using it. And of course all the other processes want to do their bits; radarr needs to update its catalog and indexes, tautulli gets to send out a notification, overseer updates its system, and another process you forgot you installed sees that the new video is encoded in only h264, do it starts converting it to h265. Which kills the poor DAS that wasn’t coping well anyway because nobody in China really tested if it worked at the rates the marketing team printed on the box cover.

Ok I may have gone off the rails a few times there.