[PLUG] CMR/PMR hard drive manufacturers and vendors

[Larry Brigman]

There are only three disk drive manufacturers left.
Western Digital
Seagate
Toshiba


On Sun, Nov 1, 2020, 1:38 PM Keith Lofstrom <keithl at kl-ic.com> wrote:

> I want to purchase more backup hard drives:
> 3.5 inch SATA, 6 to 10 TB ( best price per terabyte ),
> 5400 RPM ok, reliability important.
>
> Who makes,  and who sells, reliable "CMR" hard drives
> with a decent (3 to 5 year) full replacement warranty?
> Who should I avoid?
>
> I would especially like to hear from those who recently
> purchased drives for RAID arrays; an application with
> the same write performance requirements as mine.
>
> ----
>
> long winded explanation:
>
> Since my last backup hard drive purchases 2-3 years ago,
> "CMR/PMR" ( Conventional/Perpendicular Magnetic Recording )
> hard drives models are being replaced with "Shingled" hard
> drives, which squeeze more bytes on fewer platters, but
> have much slower write latency.
>
> Write latency (time to complete an operation) is critical
> for my backup application, which often rewrites filesystem
> directories.
>
> Shingled writes don't just rewrite sectors or tracks, but
> 256 megabyte groups of tracks.  The write head is wider
> than a readable track, so a SHINGLED write requires reading
> all 256 MB into a RAM cache, changing the sectors in RAM,
> then writing back the entire 256 MB block on top of the
> old 256 MB.
>
> This allows denser track spacing; with current technology,
> a write head is wider than a minimum-sized read head.  So,
> SMR drives write a wide track overlapping the edge of the
> previous track in the spiral ... "shingling", like the
> overlapping shingles on the roof.
>
> Clever, in the same sense as a cheapskate using both sides
> of the toilet paper.  Similarly slow and dirty, IMHO.
>
> ----
>
> I looked on Amazon (I have Prime, they deliver fast), and
> struggled through dozens of candidates that are CMR model
> names that now use SMR.  From the "Majors": Western Digital,
> Seagate, Toshiba, all of whom have been exposed as SMR
> "bait-and-switch" vendors.  Many Amazon hard drives are
> "refreshed" with a 90 day warranty.  I had to read through
> a lot of Q/A messages from users (some of whom are shills)
> to figure this out.  Frustrating.
>
> It would be nice to have new drives in a week, but I am
> in no hurry to fail over the next two years.  Amazon is
> fast and sometimes inexpensive, but not trustworthy.
> I'd rather help the startup that eats their lunch.
>
> Keith
>
> --
> Keith Lofstrom          keithl at keithl.com
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