Date: Fri, 28 Aug 2015 12:37:44 -0500 From: Brandon J. Wandersee <brandon.wandersee@gmail.com> To: Matt Smith <fbsd@xtaz.co.uk> Cc: Matthew Seaman <m.seaman@infracaninophile.co.uk>, freebsd-questions@freebsd.org Subject: Re: Replacing Drive with SSD Message-ID: <864mjj1fh3.fsf@WorkBox.Home> In-Reply-To: <20150828084643.GB1274@xtaz.uk> References: <CEAD84AD-341A-4FB9-A3A1-D0D5A550AFFD@lafn.org> <55E01DAE.1020709@infracaninophile.co.uk> <20150828084643.GB1274@xtaz.uk>
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Matt Smith writes:
> I've heard a rumour that you should never use dd with SSD drives because
> of the wear levelling stuff. Apparently SSDs automatically make sure
> that data is sent to unused flash cells so that all the cells wear
> evenly, but if you use dd on them it makes them think that every single
> cell is in use which screws this up?
I've read the same thing before, but I can't imagine it would really be
a problem if it's the first thing you do with a new disk (and the only
time you do it). Personally, though, I would just avoid using dd.
If you're making a 1:1 clone of a system--if you're copying the same
partition scheme to a newly purchased disk of the exact same make and
model--then dd is fine, but since dd can't account for partition size or
alignment, differences in block/cylinder count, filesystem settings (you
should activate TRIM and eschew SU+J *before* copying a large amount of
data over) and what-not, it's best to just create new partitions and
filesystems and use the dump/restore method.
--
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:: Brandon Wandersee ::
:: brandon.wandersee@gmail.com ::
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