Here is a link to a good article on SMR and why you should avoid it for your NAS:

https://www.servethehome.com/wd-red-smr-vs-cmr-tested-avoid-red-smr/

 

 

 

Edited February 18, 20233 yr by peterg23

Thank you Peter.

 

MrGrey.

Note that this appears to be a fairly old article. WD has since changed their branding such that WD Red drives are SMR and WD Red Plus and WD Red Pro are CMR.

As of mid 2020 "WD Red" means SMR, and "WD Red Plus" and "WD Red Pro" mean CMR.

 

https://arstechnica.com/gadgets/2020/06/western-digital-adds-red-plus-branding-for-non-smr-hard-drives/

 

Seagate has said publicly ( April 2020) that they do not use SMR in any IronWolf or IronWolf Pro drives.

 

" Seagate confirms that we do not utilize Shingled Magnetic Recording technology (SMR) in any IronWolf or IronWolf Pro drives—purpose-built for NAS solutions.

Seagate always recommends to use the right drive for the right application".

 

Edited February 18, 20233 yr by peterg23

SMR drives are perfectly fine depending on your usage patterns. If you use them for mass media storage, they work fine. This would be the write once and read many times usage pattern. Don't use them for constant churn video surveillance footage, backups, or items that are updated multiple times across it's lifetime and you'll be fine.

6 hours ago, BRiT said:

Don't use them for constant churn video surveillance footage, backups, or items that are updated multiple times across it's lifetime and you'll be fine.

And most importantly, don't use SMR HDDs as a parity drive(s).

 

https://unraid-guides.com/2021/07/21/can-unraid-use-smr-hard-drives-the-smr-vs-cmr-debate/

I don't see what the big deal is if you're using the cache/mover to speed up your file writes.  Reading

On 2/18/2023 at 5:38 PM, BRiT said:

SMR drives are perfectly fine depending on your usage patterns. If you use them for mass media storage, they work fine. This would be the write once and read many times usage pattern. Don't use them for constant churn video surveillance footage, backups, or items that are updated multiple times across it's lifetime and you'll be fine.

I think you just described the majority of the unraid people.

This link is a better reference than the pic above for Seagate drives.
https://www.seagate.com/ca/en/products/cmr-smr-list/

As long as you:

• don't use them for parity,
• don't use them a lot,
• don't mind much slower writes when the disk is getting full,
• and don't use them to rebuild failed disks,

...then you should be fine.

 

Oh and they need TRIM to maintain performance to prevent write amplification, which the Unraid array doesn't support.

 

3 hours ago, tjb_altf4 said:

• don't mind much slower writes when the disk is getting full,

These don't have performance impacts different than other drives.

 

Why would physical rust drives need TRIM? Are you sure you're not mixing up SSD drive behavior?

 

 

10 hours ago, BRiT said:

These don't have performance impacts different than other drives.

 

Why would physical rust drives need TRIM? Are you sure you're not mixing up SSD drive behavior?

 

No some SMR hard drives use trim for performance optimization. 

https://superuser.com/questions/1407990/what-does-trim-on-an-hdd-mean

Note that TRIM is just a command that any drive can support.  It's used in SMR as pointed out by primeval_god above (because the behaviour of SMR is similar to SSD) but it can also be used by a CMR drive although there's a debate (link below) about whether a CMR drive with TRIM is really just an SMR drive.  But consider that TRIM is designed to mark an allocation unit as deleted.  So instead of actually clearing all those bits you only need to mark the whole block as cleared and it's assumed that all bits in the block are cleared.  It's actually a great way to pre-clear a disk (see the Western Digital article below - in the HDD Initialization section).

 

CMR Drive with TRIM Feature

https://www.reddit.com/r/DataHoarder/comments/y1dyfp/cmr_drive_with_trim_feature/

 

Trim Command - General Benefits for Hard Disk Drives

https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/product/internal-drives/wd-purple-hdd/whitepaper-generic-benefit-for-hard-disk-drive.pdf

On 2/22/2023 at 6:07 PM, tjb_altf4 said:

As long as you:

• don't use them for parity,
• don't use them a lot,
• don't mind much slower writes when the disk is getting full,
• and don't use them to rebuild failed disks,

...then you should be fine.

 

Oh and they need TRIM to maintain performance to prevent write amplification, which the Unraid array doesn't support.

 

 

Someone tell Dropbox. 90% of their deployment is SMR.

2 hours ago, positronicP said:

 

Someone tell Dropbox. 90% of their deployment is SMR.

Hyperscalers are a completely different kettle of fish to a home nas user, besides they won't be using device managed SMR junk that we are sold, they'll be on HM-SMR.

For anyone interested in what @positronicP and @tjb_altf4 are talking about you can read about it here --> https://blog.westerndigital.com/host-managed-smr-dropbox/

 

As @tjb_altf4 points out, Dropbox uses HM-SMR (Host-managed SMR) but the host (OS) needs to be aware of this technology for it to be of use.  So for most of us we're talking about DM-SMR (Device-managed SMR - as mentioned by @tjb_altf4 above).  Maybe at some point in the future HM-SHR will be supported by Linux and unRAID.  I personally think that if you have cache drives then DM-SMR is ok as a regular drive.