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Date:      Fri, 17 Feb 2012 14:27:45 +0000
From:      Alexander Best <arundel@freebsd.org>
To:        freebsd-fs@freebsd.org
Subject:   Re: freebsd-swap on ssd
Message-ID:  <20120217142745.GA68510@freebsd.org>
In-Reply-To: <20120217141607.GA63659@freebsd.org>
References:  <20120217141607.GA63659@freebsd.org>

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On Fri Feb 17 12, Alexander Best wrote:
> hi there,
> 
> putting a freebsd-ufs partition on an ssd isn't recommended, since the ufs
> structure (unlike zfs e.g.) requires certain data to be continuously written to
> a fixed location and thus will cause the ssd to quickly run out of write-cycles
> and die.
> 
> but how about using a small ssd (approx. 10GB) as one entire freebsd-swap
> partition? will this make more sense, or are there certain structures within
> the freebsd-swap partition type, which also need to be continuously written to
> a fixed location?
> 
> another question i'd like to ask: are there also issues with read-cycles on
> ssds? because i was thinking about putting a freebsd-boot partition on an ssd
> drive and only mounting it ro. this should solve the write-cycle issue in
> theory. however i'm not sure, if stuff like the dirty bit or the ufs label will
> also remain untouched. so even though the partition will only be mounted ro,
> freebsd might still frequently write certain data to a fixed location on the
> ssd drive which hosts the freebsd-boot partition. if this is the case, is there
> a way of completely prohibiting any writes to a disk? will revoking any write
> permissions from the device entry under /dev guarantee this, or is using a any
> device 100% ro under freebsd impossible (unless it has a hardware switch to
> forbid writes)?

i'm sorry, if i was unprecise here. what i meant was to have a ssd drive with a
freebsd-boot partition on it (which of course cannot be mounted) and an extra
freebsd-ufs partition with the contents of / on it, which is the partition i'd
like to only mount ro. so again the question is: will this configuration
(freebsd-boot and freebsd-ufs (ro) partition) ensure that no writes to the ssd
are being performed?

cheers.
alex

> 
> cheers.
> alex



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