With my Network-Attached Storage rig serving as the central backup, storage, and data archival vault in my home lab, I take every precautionary measure in the tinkering bible to ensure it remains safe from harm. My overprotective nature also extends to the SSDs and HDDs (yeah, I’m a member of the two opposing storage media groups) housing my precious data, though there’s only so much I can do to extend their longevity.

Considering that storage drives tend to have some of the shortest lifespans in a home lab, I have to remain vigilant about the operational status of my HDDs and SSDs, or risk several days of downtime. While it’s true that storage drives can kick the bucket without any symptoms, there are some early warning signs that have helped me detect impending drive failures.

Warnings from S.M.A.R.T. tests

HDDs and SSDs have their own sets of critical parameters

S.M.A.R.T., or Self-Monitoring, Analysis, and Reporting Technology, is a neat facility built into storage drives that provides detailed reports of their operational parameters, and these statistics can clue you in about the condition of your drives. Reallocated sector count, for instance, tells the number of times your drive has successfully redirected write/read operations meant for a faulty sector to one that’s free of errors. While it’s common to see a couple of reallocated sectors in aged drives, a high number can spell trouble. Then there’s the more concerning variant, Uncorrectable Sector Count, which notifies you about the number of inaccessible sectors that can’t remap data to spare sectors.

You’ve also got S.M.A.R.T. metrics exclusive to the SSD and HDD factions. SSDs, for example, have Erase Fail Count and Wear Level Count metrics that you need to look out for, with the former denoting the exact times an SSD couldn’t properly erase data from NAND flash cells. Meanwhile, Wear Leveling is a facility used by SSDs to assign the operations evenly to different flash cells, and its S.M.A.R.T. attribute is an indicator of the amount of life left in the drive.

On the flip side, hard drives include a unique metric called Spin Retry Count, which measures the number of times your HDD has to rotate platters during file transfer operations. There’s also the Seek Error Rate, and it can tell you how often the HDD couldn’t find the right track on the platter. High values for both could be caused by excessive vibrations, but if your drives indicate the other errors on this list, it might be time to replace them.

Weird screeching noises from drives

Hard drives aren’t supposed to be that noisy

While we’re on the subject of hard drives, you’re probably familiar with the amount of ruckus they can make during normal operations. Since they’re mechanical in nature, the motors and read/write heads of HDDs can make humming or clicking sounds during normal file transfer operations.

However, if your drives start making loud screeching, grinding, or rapid clicking sounds, they might be experiencing mechanical failures. And in case the scratching noises don’t stop even when the HDD is idling, you’re better off checking their S.M.A.R.T. values for Spin Retry Count and Seek Error Rate statistics.

File transfer operations take forever

There’s definitely something fishy going on in your storage pool

The amount of time taken by read and write tasks can depend on several factors, including the networking ports on your NAS (and client), the presence of RAM caches, and, more importantly, the drives in your storage pools. In fact, even different RAID levels can heavily affect the transfer speeds of your NAS. But if the read/write operations take too long, you should don your troubleshooting hat.

Unless there’s something wrong with your network, there’s a good chance your drives could be the culprits. Perhaps your HDD developed some slow sectors, and they’re tanking your transfer speeds. Or maybe one of the drives in your RAID pool has already given out and caused it to go into a degraded state. Heck, you might even have an SMR drive mixed in there, which can cause pathetic write speeds whenever you try overwriting old files.

Files become inaccessible out of nowhere

Data corruption is code red for a NAS

If your NAS gives you trouble when you try accessing data on your network shares – and I don’t mean problems caused by incorrect NFS permissions – it’s entirely possible that bad sectors have caused the files to become unreadable. Sure, between the write-hole problem plaguing certain RAID levels and firmware issues in the underlying distro, there are a couple of ways your data pools can become corrupted.

However, bad sectors on hard drives can also result in your NAS throwing weird errors when you try opening your files, including missing directories and file names with random characters.

Always keep hot spares and schedule regular backups

Although I’ve highlighted a bunch of symptoms of dying storage drives, it’s also highly likely that they might kick the bucket without displaying any signs whatsoever. That’s why I always recommend 3-2-1 backups, so you won’t end up losing anything important if anything happens to your NAS drives. For folks relying on RAID pools as much as I do, you might want to consider adding a hot spare (or maybe even two for higher RAID levels) to your NAS, as it cuts down the recovery time by rebuilding the datasets as soon as it detects a failed drive.