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?
Probably best to go with something in the 3.5" line, unless you’re going enterprise 2.5" (which are entirely different birds than consumer drives)
Whatever you get for your NAS, make sure it’s CMR and not SMR. SMR drives do not perform well in NAS arrays.
Many years ago I for some low cost 2.5" Barracuda for my servers only to find out years after I bought them that they were SMR and that may have been a contributing factor to them not being as fast as I expected.
TLDR: Read the datasheet
Whatever you get for your NAS, make sure it’s CMR and not SMR. SMR drives do not perform well in NAS arrays.
I just want to follow this up and stress how important it is. This isn’t “oh, it kinda sucks but you can tolerate it” territory. It’s actually unusable after a certain point. I inherited a Synology NAS at my current job which is used for backup storage, and my job was to figure out why it wasn’t working anymore. After investigation, I found out the guy before me populated it with cheapo SMR drives, and after a certain point they just become literally unusable due to the ripple effect of rewrites inherent to shingled drives. I tried to format the array of five 6TB drives and start fresh, and it told me it would take 30 days to run whatever “optimization” process it performs after a format. After leaving it running for several days, I realized it wasn’t joking. During this period, I was getting around 1MB/s throughput to the system.
Do not buy SMR drives for any parity RAID usage, ever. It is fundamentally incompatible with how parity RAID (RAID5/6, ZFS RAID-Z, etc) writes across multiple disks. SMR should only be used for write-once situations, and ideally only for cold storage.
2.5" disks are SMR, you don’t want that in a raid.
For the record, so are a lot of 3.5s. Always read up on your drives before buying.
the 3.5" barracuda disks are SMR. the barracuda pro disks are all CMR. https://www.seagate.com/products/cmr-smr-list/
SMR ? What is that
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.
The 2.5 unit I have runs cooler and consumes less power. It’s also more expensive.
Just buy CMR
I don’t think there’s anything between.
lol - just realised that probably wasnt the best formulation for a question ahah
Well you’re looking at it. 3.5in is faster
Generally higher storage sizes too, right? So if you want the max storage, go with 3.5"
Cheaper too I guess
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 )
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.
