Comment on Help choosing a good HDD for my home server?
solrize@lemmy.ml 4 days ago
While I don’t exactly intend to run RAID, I ended up choosing nas drives for the 24/7 intended usage,
The purpose of a NAS drive is to be LESS reliable than a regular drive, not more reliable. Explanation: if a regular drive gets a read error on a block, it will retry for quite a while before giving up. The host, meanwhile, has to wait for the data to be retrieved if the retries work. That’s all it can really do, wait and hope. Meanwhile, the waiting slows the application down.
A NAS drive instead will fail once or twice, then give up immediately, since it knows that it’s in a RAID system and that the data is also present on other disks. The RAID then puts the data together from the other drives and gets it to the host, logging the error. It will also hopefully mark the bad block on the drive with the read failure, and rewrite the recovered data to a spare sector. So this is faster than all the retries even though the drive that had the bad block gives up on it rather than attempting recovery by repeated reads.
So if you buy NAS drives, put them in a RAID.
Drives are currently around 2x as expensive as a year or so ago but they are available if you can afford them. I guess that’s better than shortages where they’re hard to find even if you can pay. We’ve had that before too.
I like to think the current situation will settle out. Who knows though. Drive space is still way less expensive than in 2010 or anything like that.
FierroG@lemmy.world 4 days ago
Interesting, Hadn’t really read anything like that before, since nas drives have extra features and functions that seems like a thing they would set as an extra flag or something (if it’s running on raid, then give up sooner).
What I meant by reliability was more about running the drive 24/7, as far as I could see they’re the only ones intended to be used that way (besides surveilance drives). They are intended to run at all times, spin more frequently and sustain more vibrations from nearby drives as well as heat, I feel like there’s more to it than that but can’t say myself.
Do you mean that the drive will say it’s dead if there are errors?
solrize@lemmy.ml 3 days ago
IDK really. I’m repeating what I saw someplace years ago. I would say do a real RAID if you manage it. Maybe RAID 5 on 3 drives.
MuttMutt@lemmy.world 3 days ago
If a NAS or Enterprise drive has an error it sends the information to the host to be logged so that the end user can have the information available.
So like an Unrecoverable Read Error (URE) pops up on a sector. A drive that is built for RAID use will just say, “Couldn’t read it” and moves on. A Consumer drive meant for a desktop will try and try and try and try to read that bad sector. In a NAS situation where another drive will be able to fill in the data the controller (hardware or software) will just deal with it by pulling the data from another drive and keep moving.
The drive may not be bad as a whole but it does mean that over time it is more likely that drive will have more errors.
NAS drives are not inherently more reliable, yes they can deal with a bit more vibration and such but it’s the firmware inside that is different. Enterprise drives are another step up again from NAS drives.
FierroG@lemmy.world 3 days ago
So instead I should aim for a barracuda or a wd black or blue?
MuttMutt@lemmy.world 3 days ago
I’m not saying that.
What you need to do is decide now if the drive you will buy will be used for a RAID array. If it is a desktop drive won’t be in a RAID array on a NAS system. Many NAS’ will have random writes to the pool. Desktop drives aggressively park the heads, the load and unload of the heads wears them. In a NAS system they can actually wear out.
Over the last 15 years drives have become a bit more specialized. You already found out about surveillance drives not being a good fit for much other than surveillance/DVR. Desktop drives are fine for desktop loads and usage but outside of that or single drive usage they are not useful. NAS drives are meant for NAS usage in RAID arrays. Back when the WD green drives were available years ago you could convert them from a desktop drive to a NAS drive using a tool called wdidle (WD Idle) but that isn’t the case any more.
Using a NAS drive on its own will work in a pinch but if it has an error it won’t try to recover it like a Desktop drive would because it’s made with the idea that it will be in an array that will deal with the issue. Plus once you start loading it up you will have to wipe it to put it into an array unless you go for ZFS mirrors or RAID 1. If the NAS Appliances have some sort of special trickery that allows you to expand one disk at a time and add redundancy I’m completely unaware as I’ve never put much stock in them. I’ve been running FreeNAS/TrueNAS for over 10 years.
en.wikipedia.org/wiki/Standard_RAID_levels