[clug] Western Digital: some RED drives using SMR, Shingled Magnetic Recording

[Peter Ellis]

Let me guess, they used the slide rule around the dial of their watch to
design this scheme.

And, I am a real slide rule fan!

Peter
Normally a lurker.....

On Wed., 3 Jun. 2020, 17:35 steve jenkin via linux, <linux at lists.samba.org>
wrote:

> If you’ve bought WD Red drives for a home or SME NAS in the last while,
> they may not perform as you expect.
>
> Shingled drives write a wide stripe, intentionally overwriting part of the
> previous track, leaving a thin but readable track.
>
> SMR drives write to contiguous blocks very well, but “Update in Place”
> requires reading / rewriting an entire “Zone”.
> The concept is closest to Optical Drives (RO or RW) where a volume could
> be left “open” for updates or  “closed” and nothing more written.
>
> There’s a US class action underway based on this, based on an
> investigation by Chris Mellor of El Reg.
>
> The chart WD provides has a little surprise (at least for me).
> WD’s 2.5” drives, WD-Blue and Black are SMR.
>
> =====================
>
> On WD Red NAS Drives
> <https://blog.westerndigital.com/wd-red-nas-drives/>
>
>
> Current SKU’s using SMR
> <
> https://blog.westerndigital.com/wp-content/uploads/2020/04/2020_04_22_WD_SMR_SKUs_1Slide.pdf
> >
>
> =====================
>
> Zonefs File-System Will Land with Linux® 5.6
> <https://blog.westerndigital.com/zonefs-file-system-linux-5-6/>
>
>  Zonefs is not a general-purpose file-system like the famous XFS or ext4.
> Legacy, unmodified applications will not be able to take advantage of
> zonefs.
>
> Zonefs allows is to simplify the implementation of zoned block devices
> support in applications by replacing raw block device file accesses with
> the richer set of regular file system calls.
> This means, for instance, that developers do not have to rely on direct
> block device file ioctls, which can be far more obscure.
>
> =====================
>
> Zoned Storage
> <https://blog.westerndigital.com/what-is-zoned-storage-initiative/>
> Zoned Storage Devices are block storage devices that have their address
> space divided into zones.
>
> ZSDs impose unconventional writing rules:
>         zones can only be written sequentially and starting from the
> beginning of the zone.
>         In addition, data within a zone cannot be arbitrarily overwritten.
>
> The Linux kernel work on zoned storage started back in 2014 with the most
> minimal amount of support incorporated into the 3.18 kernel.
> The first kernel release with functional ZBC/ZAC command support was
> kernel 4.10 in early 2017.
> The support has continued to improve, and the most recent kernels have
> device-mapper support as well as some filesystem support.
>
> =====================
>
> --
> Steve Jenkin, IT Systems and Design
> 0412 786 915 (+61 412 786 915)
> PO Box 38, Kippax ACT 2615, AUSTRALIA
>
> mailto:sjenkin at canb.auug.org.au http://members.tip.net.au/~sjenkin
>
>
> --
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>