Most of the hard disk model from all manufacturers are SMR based now a days , though they do not disclose this fact.
SMR drives are either 5400 / 5700 RPM based I think pls. correct me if I am wrong.
I have read everywhere that these drives perform less in writting.
Can someone pls. clarify how much is difference in performance is there besides any other cons with SMR drives. I have read that RPM is not the only parameter for calculating performance. SMR drives have 128MB cache while CMR drives have 64MB.

There have been a number of in-depth articles and comparisons done by the usual sources (LTT, ServetheHome, LevelOneTechs etc). https://www.servethehome.com/wd-red-smr-vs-cmr-tested-avoid-red-smr/ for example.

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Data Recovery Services in the UK.
https://www.usbrecovery.co.uk/

SMR sucks when you need to write large amount of data. The transfer speed drops drastically, to about 15-20MB/sec as it runs out of T2 space or MC space.
For some larger 3.5" drives it takes longer to fill up, but it gets to that point sooner or later.
Copying 2TB to an usb WD (charger) drive can take 1-2 days :s

pepe

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Adatmentés - Data recovery

Wrong.

A quick look into a search engine for 3,5'' drives gives:

Energy Assisted Conventional Magnetic Recording (EAMR CMR)(4)
Conventional Magnetic Recording (CMR)(627)
Two Dimensional Magnetic Recording (TDMR)(5)

Shingled Magnetic Recording (SMR)(31)
non-SMR(631)
Drive Managed SMR(31)


Selecting SMR drives gives the following manufacturers:

Intenso(1) Seagate(11) Toshiba(8) Western Digital(11)

Obviously these companies do not hide this information.

Where did you get your information from?!

I expect the OP means they failed to advertise the fact they were SMR rather than tried to hide the fact they were. It's a distinction without a difference from an end user point of view though. WD/Seagate came clean after customers called them out on it.

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Data Recovery Services in the UK.
https://www.usbrecovery.co.uk/

WD's support staff originally refused to tell, or were unable to tell, customers whether a particular model used SMR or CMR. There are plenty of threads in WD's forum on the subject, some of them laughable.

WD is now facing a class action law suit which charges that they "submarined" SMR drives into their NAS products.

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A backup a day keeps DR away.

SMR are everywhere RED / BLACK Green , NAS etc.
Lardam has rightously said Mfrs. have hidden this information.

How Avergae Consumer or even technician will come to know which is SMR / CMR ?

There's this list of known SMR drives, on the TrueNAS site.

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Sabo Computer Repairs & Data Recovery

What WD and HGST hard drives are SMR?
https://hddscan.com/blog/2020/hdd-wd-smr.html

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A backup a day keeps DR away.

Thank you for insisting!

I just (4.7.2021 121:03 UTC+2) downloaded a WD Blue data sheet and attached it to this posting:

https://documents.westerndigital.com/co ... 771436.pdf

There is no information about the recording technology inside!

True, but you can find the recording technology on the individual product page:

https://shop.westerndigital.com/products/internal-drives/wd-blue-desktop-sata-hdd#WD60EZAZ

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A backup a day keeps DR away.

Here they try to whitewash their fraudulous omission of non-disclosure of SMR drives:

https://blog.westerndigital.com/wd-red-nas-drives/

They write the SMR info into the blog but have not updated their datasheets.
If I need information I look into the datasheet - shame on them!

They state:
[...
From our experience, we see most SOHO users rely on their systems for office file sharing, home backup or content archiving.
...]

Funnily they redefine SOHO in a way that it fits SMR specifics and ignore the fact that users may use the drive as working drives not wanting to use SSD technology for their data.
I doubt that SOHO users who rarely do backups are using the WD Reds for "home backup or content archiving"...

One other thing you need to know is that many WD/HGST "5400 RPM class" drives actually spin at 7200 RPM. In the past WD's employees, in their own forum, were falsely proclaiming that their IntelliPower drives varied their spin speed from 5400 RPM to 7200 RPM according to workload. In fact they were designed to spin at a constant speed, usually 5400 RPM.

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A backup a day keeps DR away.