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Date:      Sun, 14 Jul 2019 07:10:26 +0200
From:      hw <hw@adminart.net>
To:        "Kevin P. Neal" <kpn@neutralgood.org>
Cc:        "Clay Daniels Jr." <clay.daniels.jr@gmail.com>, freebsd-questions@freebsd.org
Subject:   Re: dead slow update servers
Message-ID:  <87v9w58apd.fsf@toy.adminart.net>
In-Reply-To: <20190714011303.GA25317@neutralgood.org> (Kevin P. Neal's message of "Sat, 13 Jul 2019 21:13:03 -0400")
References:  <87sgrbi3qg.fsf@toy.adminart.net> <20190712171910.GA25091@neutralgood.org> <871ryuj3ex.fsf@toy.adminart.net> <CAGLDxTW8zw2d%2BaBGOmBgEhipjq6ocn536fH_NScMiDD7hD=eSw@mail.gmail.com> <874l3qfvqw.fsf@toy.adminart.net> <20190714011303.GA25317@neutralgood.org>

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"Kevin P. Neal" <kpn@neutralgood.org> writes:

> On Sat, Jul 13, 2019 at 05:39:51AM +0200, hw wrote:
>> ZFS is great when you have JBODs while storage performance is
>> irrelevant.  I do not have JBODs, and in almost all cases, storage
>> performance is relevant.
>
> Huh? Is a _properly_ _designed_ ZFS setup really slower? A raidz
> setup of N drives gets you the performance of roughly 1 drive, but a
> mirror gets you the write performance of a titch less than one drive
> with the read performance of N drives. How does ZFS hurt performance?

Performance is hurt when you have N disks and only get the performance
of a single disk from them.

Mirroring the N disks would require another N disks, which you don't
have.

"Performance" isn't much better defined as "properly designed" here.  In
practise, I prefer a hardware RAID5 with N disks over a raidz with N
disks and a RAID10 over a RAID5.  Unfortunately, in practise, the number
of disks is limited because they aren't cheap and because only so many
disks can be connected to a machine without further ado while there is a
certain requirement for storage capacity.  Reality is not proper
designed :/


What do you do when you put FreeBSD on a server that has a hardware RAID
controller which doesn't do JBOD?  Use ZFS on the RAID?



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