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<9bafdc79-a77f-1b57-6372-b611176164f4@youngman.org.uk> <1756899.CQOukoFCf9@lenovo.localdomain>
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From: Rich Freeman <rich0@gentoo.org>
Date: Fri, 22 May 2020 11:43:24 -0400
Message-ID: <CAGfcS_kWxr_o40dbsNnmzi4F2Cz2yZSvMN8z2vtdhoNdTgWV+Q@mail.gmail.com>
Subject: Re: [gentoo-user] Seagate ST8000NM0065 PMR or SMR plus NAS SAS SATA question
To: gentoo-user@lists.gentoo.org
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On Fri, May 22, 2020 at 11:32 AM Michael <confabulate@kintzios.com> wrote:
>
> An interesting article mentioning WD Red NAS drives which may actually be SMRs
> and how latency increases when cached writes need to be transferred into SMR
> blocks.
Yeah, there is a lot of background on this stuff.
You should view a drive-managed SMR drive as basically a journaled
filesystem/database masquerading as a virtual drive. One where the
keys/filenames are LBAs, and all the files are 512 bytes long. :)
Really even most spinning drives are this way due to the 4k physical
sectors, but this is something much easier to deal with and handled by
the OS with aligned writes as much as possible. SSDs have similar
issues but again the impact isn't nearly as bad and is more easily
managed by the OS with TRIM/etc.
A host-managed SMR drive operates much more like a physical drive, but
in this case the OS/application needs to be SMR-aware for performance
not to be absolutely terrible.
--
Rich