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List of known SMR drives

Hard drives that write data in overlapping, "shingled" tracks, have greater areal density than ones that do not. For cost and capacity reasons, manufacturers are increasingly moving to SMR, Shingled Magnetic Recording. SMR is a form of PMR (Perpendicular Magnetic Recording). The tracks are perpendicular, they are also shingled - layered - on top of each other. This table will use CMR (Conventional Magnetic Recording) to mean "PMR without the use of shingling".

SMR allows vendors to offer higher capacity without the need to fundamentally change the underlying recording technology.
New technology such as HAMR (Heat Assisted Magnetic Recording, Seagate) or MAMR (Microwave Assisted Magnetic Recording, WD) can be used with or without shingling. The first drives are expected in 2020, in either flavor.

SMR is well suited for high-capacity, low-cost use where writes are few and reads are many.

SMR has worse sustained write performance than CMR, which can cause severe issues during resilver or other write-intensive operations, up to and including failure of that resilver. It is often desirable to choose a CMR drive instead. This thread attempts to pull together known SMR drives, and the sources for that information.

There are three types of SMR:
- Drive Managed, DM-SMR, which is opaque to the OS. This means ZFS cannot "target" writes, and is the worst type for ZFS use. As a rule of thumb, avoid DM-SMR drives, unless you have a specific use case where the increased resilver time (a week or longer) is acceptable, and you know the drive will function for ZFS during resilver. See (h)
- Host Aware, HA-SMR, which is designed to give ZFS insight into the SMR process. Note that ZFS code to use HA-SMR does not appear to exist. Without that code, a HA-SMR drive behaves like a DM-SMR drive where ZFS is concerned.
- Host Managed, HM-SMR, which is not backwards compatible and requires ZFS to manage the SMR process.

I am assuming ZFS does not currently handle HA-ZFS or HM-ZFS drives, as this would require Block Pointer Rewrite. See page 24 of (d) as well as (i) and (j).

List of SMR drives known to the community:

Manufacturer - WidthModel NoModel NameTypeNotes
WD - 3.5"WD20EFAX2TB WD RedDM-SMR(1) and (4), EFRX is CMR
WD - 3.5"WD40EFAX4TB WD RedDM-SMR(1) and (4), EFRX is CMR
WD - 3.5"WD60EFAX6TB WD RedDM-SMR(1) and (4), EFRX is CMR
WD - 3.5"WD20EZAZ2TB BlueDM-SMR(4), EZRZ is CMR
WD - 3.5"WD60EZAZ6TB BlueDM-SMR(4), EZRZ is CMR
WD - 3.5"VariousAll 2-6TB external drives - Elements, My Book, Easystore, etc. Precise models vary and are not guaranteed; assume SMR in capacities below 8TB.DM-SMR(12), (14)
Seagate - 3.5"ST2000DM0052TB BarracudaDM-SMR(8)
Seagate - 3.5"ST2000DM0082TB BarracudaDM-SMR(2)
Seagate - 3.5"ST3000DM0073TB BarracudaDM-SMR(8)
Seagate - 3.5"ST4000DM0044TB BarracudaDM-SMR(2)
Seagate - 3.5"ST5000DM0035TB BarracudaDM-SMR(8)
Seagate - 3.5"ST6000DM0036TB BarracudaDM-SMR(8)
Seagate - 3.5"ST8000DM0048TB BarracudaDM-SMR(2)
Seagate - 3.5"ST5000DM0005TB DesktopDM-SMR(2)
Seagate - 3.5"ST5000AS00115TB ArchiveDM-SMR(3)
Seagate - 3.5"ST6000AS00026TB Archive v2DM-SMR(3)
Seagate - 3.5"ST8000AS00028TB Archive v2HA-SMR(3) and (10)
Seagate - 3.5"ST8000AS00038TB Exos (Archive v3)DM-SMR(2)
Seagate - 3.5"ST1000VX0081TB Skyhawk LiteDM-SMR(8)
Seagate - 3.5"ST2000VX0072TB Skyhawk LiteDM-SMR(8)
Toshiba - 3.5"HDWD240UZSVA4TB P300 DesktopDM-SMR(11)
Toshiba - 3.5"HDWD260UZSVA6TB P300 DesktopDM-SMR(11)
Toshiba - 3.5"DT02ABA4004TB DT02(-V)DM-SMR(11)
Toshiba - 3.5"DT02ABA6006TB DT02(-V)DM-SMR(11)
HGST - 3.5"DC HC600 Series14TB, 15TB and 20TB UltrastarHM-SMR(9)
Toshiba - 2.5"HDWL1101TB L200 SlimDM-SMR(11)
Toshiba - 2.5"HDWL1202TB L200DM-SMR(11), see also list at (18)
Toshiba - 2.5"MQ04ABF1001TB MQ04DM-SMR(11)
Toshiba - 2.5"MQ04ABD2002TB MQ04DM-SMR(11)
WD - 2.5"WD9000LPZX900GB BlueDM-SMR(16)
WD - 2.5"WD10SPZX1TB BlueDM-SMR(4), also as HGST Travelstar, see (20)
WD - 2.5"WD10SPWX1TB BlueDM-SMR(16)
WD - 2.5"WD10SPSX1TB BlackDM-SMR(4)
WD - 2.5"WD20SPZX2TB BlueDM-SMR(4)
WD - 2.5"VariousNot For ResaleDM-SMRList at (17)
Seagate - 2.5"ST1000LM0481TB BarracudaDM-SMR(7), see also list at (19)
Seagate - 2.5"ST2000LM0152TB BarracudaDM-SMR(7), see also list at (19)
Seagate - 2.5"ST3000LM0243TB BarracudaDM-SMR(7), see also list at (19)
Seagate - 2.5"ST4000LM0244TB BarracudaDM-SMR(7), see also list at (19)
Seagate - 2.5"ST5000LM0005TB BarracudaDM-SMR(7), see also list at (19)
Seagate - 2.5"All current Barracuda, Firecuda, Skyhawk Lite/Mini modelsDM-SMR(8)

More info on SMR:

(a) HA-SMR and HM-SMR in ZFS: 2014, Tim Feldman of Seagate,
(b) HA-SMR presentation, recording: 2014, Tim Feldman,
(c) HA-SMR education: 2014, Mary Dunn and Tim Feldman of Seagate,
(d) ZFS on SMR: 2014, Robert Novak,
(e) HM-SMR paper: 2013, Albert Chen et al, WD:
(f) DM-SMR and CMR zones, resilvering woes:
(g) Code to make ext4 HA-SMR aware: 2015, Seagate,
(h) Performance and resilver results of using Seagata Archive v2 8TB on FreeNAS:
(i) The intricacies of BPR: 2013, Matt Ahrens,
(j) BPR is so complex no new features can be added afterwards: 2020, BSD Now podcast, from roughly 22:00,
(k) SMR presentation: 2015, Manfred Berger HGST,
(l) OpenZFS Office Hour discussion on SMR: 2015, SMR, Resilvering, Possible Solutions at around 20, 31 and 46 mins respectively,
(m) SAFS example file system for HA-SMR: 2015, Huewai R&D,
(n) HiSMRFs research file system for SMR: 2014,
(o) Poster for Zone-based Storage Tiering for HA-SMA: 2017, University of Minnesota, Archive/tech_poster/poster_files/post204s2-file2.pdf
(p) Manylogs concept, platters would need SMR and CMR sides: 2016, IEEE,
(q) Toshiba presentation on SMR technology: 2015,

Sources for "drive is SMR" assertions

(1) WD Red 2TB to 6TB are DM-SMR:
(2) Seagate drives that use DM-SMR:
(3) Seagate data sheet for DM-SMR Archive drives:
(4) WD list of SMR drives:

(7) Anandtech lists Seagate 2.5" Barracuda as SMR:
(8) Seagate's list of SMR drives:
(9) HGST Host-Managed SMR DataCenter drives:
(10) Seagate datasheet for 8TB Archive v2 showing HA-SMR:
(11) Toshiba's list of DM-SMR drives:
(12) WD platter sizes:|
(13) WD data sheet for WD Red, note 256MB cache suggesting DM-SMR:
(14) WD platter sizes niche products:
(15) Seagate platter sizes:
(16) WD platter sizes 2.5":
(17) WD platter sizes 2.5 niche products:
(18) Toshiba platter sizes 2.5":
(19) Seagate platter sizes 2.5":
(20) HGST platter sizes 2.5":
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Very helpful in avoiding SMR garbage
Thanks for the info.
This is great list and resource for understanding vendor's use of SMR drives when then they did not clearly identify them as such. In fact, this resource seems to have caught the Internet's attention.
very useful overview, thanks