Been finding some good deals on 2.5 disks lately, but have never bought one before. Have a couple of 3.5 disks on the other hand in my Unraid server. Wondering how much it matters wether I get a 2.5 or not? What form factor do you prefer/usually go for?
2.5" disks are SMR, you don’t want that in a raid.
SMR is a relatively new disk format technology that makes drives cheaper but writes slower, which can be noticeably bad in a NAS, especially if you are using a write-intensive RAID type. Most disk manufacturers will have drives meant for NAS like WD Red or Seagate Ironwolf, and they are almost all CMR and not SMR.
WD reds I believe are smr, wd red pros are cmr, or at least that was a thing for a while that WD did silently.
Basically the write head writes over part of the magnetic track below the current track, reducing the physical size of each data and increasing how much data can be stored on one side of a disk.They’re bad for random writes because the drive would need to rewrite data in the track below it as well.
For the record, so are a lot of 3.5s. Always read up on your drives before buying.
Here you can check if a drive is CMR or SMR:
https://nascompares.com/answer/list-of-wd-cmr-and-smr-hard-drives-hdd/
the 3.5" barracuda disks are SMR. the barracuda pro disks are all CMR. https://www.seagate.com/products/cmr-smr-list/
Just buy CMR
Well first off, if you’re building a NAS, build it out of drives that are rated for NAS use. Seagate’s IronWolf line is a bit pricier than their BarraCuda but has better transfer speeds and (more importantly) better resiliency to vibration, which is important if you’re putting a half dozen drives in the same enclosure and don’t want them to fail prematurely.
Depends on your NAS server. If you’re like me and using an old optiplex, you can fit WAY more 2.5" drives in it, and they’re pretty cheap. If you have an actual proper server chassis, then you probably want 3.5" NAS hard drives cuz warranty and all that.
Power-consumption.
Also, the vibration produced by the 2.5" drives is less, but they’re more-sensitive to it, to begin with.
I’d not even consider spinning-platter drives, nowadays, though:
SATA SSD’s for a NAS strike me as being the sanest choice.
Samsung what are those called, Evo drives?
excellently-high MTBF, ultra-short ( compared with rotating-platters ) seek-time ( literally orders-of-magnitude quicker ), etc.
I don’t know of ANY reason to go with spinning-platters, nowadays.
( & I’m saying that as a guy stupid-enough to have not realized this in time, & who spent money on such a thing, when SSD’s really were the answer )
I don’t know of ANY reason to go with spinning-platters, nowadays.
Price per terabyte is lower on HDDs. For bulk storage they are currently the best path. SSDs are catching up though, and there are cases where a SSD based NAS does make sense. But most folks at home don’t have the network capability to fully utilize their speed. Network becomes the bottleneck.
Running ZFS on consumer SSDs is absolute no go, you need datacenter-rated ones for power loss protection. Price goes brrrrt €€€€€
I too had an idea for a ssd-only pool, but I scaled it back and only use it for VMs / DBs. Everything else is on spinning rust, 2 disks in mirror with regular snapshots and off-site backup.
Now if you don’t care about your data, you can just spin up whatever you want in a 120€ 2TB ssd. And then cry once it starts failing under average load.
Edit: having no power loss protection with ZFS has an enormous (negative) impact on performance and tanks your IOPS.
