NAS drives cost more than desktop drives, and one firmware timeout has long been part of the reason

Published Oct 1, 2026, 8:00 AM EDT Maker, meme-r, and unabashed geek, Joe has been writing about technology since starting his career in 2018 at KnowTechie. He's covered everything from Apple to apps and crowdfunding and loves getting to the bottom of complicated topics. In that time, he's also written for SlashGear and numerous corporate clients before finding his home at XDA in the spring of 2023. He was the kid who took apart every toy to see how it worked, even if it didn't exactly go back together afterward. That's given him a solid background for explaining how complex systems work together, and he promises he's gotten better at the putting things back together stage since then. Let's face it, most of us buy NAS drives on faith. I certainly did, and every hard drive in my NAS is a NAS or enterprise model because that's what you're told to put in one. Ask why, and the answer often comes back as a single firmware timeout that determines how long a drive keeps fighting a bad sector before it gives up. It's not the only specification you should pay attention to, but it's an important one for when using RAID. That timeout goes by three names: TLER on WD drives, ERC on Seagate, and CCTL on Samsung and Hitachi. It's been a spec-sheet bullet since WD's RE4 server drive advertised it in 2009, and it's a big reason people tell you to buy the best hard drives for NAS instead of whatever's cheapest. So I asked my own drives what they were set to, and the number wasn't the one I expected. What a drive is doing when it stops responding Patience is a virtue, until RAID gets involved Credit: Western DigitalCredit: Picture a drive hitting a sector it can't read cleanly. A desktop drive will keep rereading it, adjusting and retrying, because it assumes it holds the only copy of your data and giving up means losing it. That's the right call for a lone drive in a PC, and it's why desktop drives have traditionally shipped with the limit switched off. In an array, that stubbornness backfires. Once you set up RAID in a NAS, another copy of that data sits on a different drive, and the array would rather rebuild the sector from there than wait. Hardware RAID controllers drop a drive that stalls past their command timeout, while Linux waits 30 seconds by default before resetting a drive that's gone quiet. A time-limited drive gives up early, reports the error, and lets the array fix it, saving you time and your data. My hard drives didn't match the number everyone quotes They wait for 10 seconds, not 7 Most TLER explainers quote 7 seconds because that's what WD's drives use. My Synology DS1621xs+ currently runs two Seagate ST20000NM007D drives in a RAID 1 pool, both on firmware SN01, so I SSHed in and asked smartctl what they were set to: sudo smartctl -l scterc /dev/sde Both drives returned 10 seconds for reads and writes. Honestly, that's fine, because 10 seconds still sits comfortably inside Linux's 30-second window. I haven't confirmed that DSM keeps the kernel default, but a drive that bails after 10 seconds isn't the one getting kicked out of the array. Changing it takes one command, and it survived a reboot So, it's time for a little experiment. Because both drives are the same model on the same firmware, I could use one as a control. I changed sde to 7 seconds and left sdf alone, remembering that smartctl counts in tenths of a second: sudo smartctl -l scterc,70,70 /dev/sde After a reboot, sde still read 7.0 seconds and sdf still read 10.0. The drive kept my settings, and nothing in DSM restored them. Drive What I did After the reboot sde Set to 7.0 seconds 7.0 seconds sdf Left alone 10.0 seconds I didn't find anything in DSM that sets this value, so I'm treating 10 seconds as the factory default. That's an inference from a search of a few directories, not proof, and a reboot isn't the same as pulling the power, so I can't promise the setting will survive a hard power-off. I checked the usual suspects for where a script might have been added and found nothing on my NAS. But that's not the important thing; it's that any Linux-based machine can edit this timeout, as long as the hard drives support it. The label matters less than what's under it Some desktop drives can't do this, and some NAS drives fail anyway This is where the NAS premium earns its keep. Seagate's own explainer lists ERC as unavailable in desktop-class drives, and on a drive without it, smartctl simply reports that the command isn't supported. Your only fallback, then, is telling Linux to wait longer, and that guide suggests 180 seconds, so a desktop drive's marathon retries don't reset it. The NAS badge isn't a guarantee either. Hard drives quietly changed how they write data, and WD's Red EFAX models turned out to be drive-managed SMR that ServeTheHome found struggling through a ZFS resilver. A drive can have a perfectly sensible timeout and still stall a rebuild, so the timeout is only one line on the spec sheet worth reading. I'd still pay for the timeout, just not for the label alone My hard drives shipped with a sensible limit, accepted a new one in seconds, and remembered it. That doesn't explain the whole price gap, but it's a real feature, and I'd rather own a drive that has it than one that doesn't. Two minutes over SSH will tell you where your own drives stand, so run the read command on each one before you need to know. While you're in there, check the S.M.A.R.T. attributes that actually predict drive failure too. And if a drive says it doesn't support the command at all, it's better to find out now than halfway through a rebuild.