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Date: Tue, 24 Mar 2015 16:39:09 +0000
Message-ID: <CAFHbX1KLSuES8rJ1Nzho7g8kj-mD_vRAuCyYvdEK9xpz49QBZA@mail.gmail.com>
Subject: Re: Zoned Commands ZBC/ZAC, Shingled SMR drives, ZFS
From: Tom Evans <tevans.uk@googlemail.com>
To: Shehbaz Jaffer <shehbazjaffer007@gmail.com>
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Cc: FreeBSD FS <freebsd-fs@freebsd.org>, grarpamp <grarpamp@gmail.com>,
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On Tue, Mar 24, 2015 at 12:47 PM, Shehbaz Jaffer
<shehbazjaffer007@gmail.com> wrote:
> Hi,
>
> I was wondering what cost advantage do SMR drive provide as compared to
> normal CMR drive?
>
> 8TB SMR drive - $ 260
> 3TB CMR (Conventional Magnetic Recording drive) - $ 105
>

Purchase price is not irrelevant, but the key benefits are increased
capacity per disk, and reduced power usage per disk and (multiplied by
the increase in capacity) per TB. In other words, they disks consume
less power, you need fewer of them, maybe allowing you to run fewer
servers.

Of course, you also need a mainly read only workload. The RAID rebuild
test from the linked review is *scary*. I wouldn't use these in ZFS
raidz without plenty of disaster recovery testing - how long does it
take to re-silver the pool when you lose a disk and what is the
performance characteristics of the pool whilst it is doing so.

Cheers

Tom