Date: Fri, 17 Feb 2012 16:35:24 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-fs@freebsd.org Subject: Re: freebsd-swap on ssd Message-ID: <jhls3t$gft$1@dough.gmane.org> In-Reply-To: <20120217141607.GA63659@freebsd.org>
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[-- Attachment #1 --] On 17/02/2012 15:16, 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. This is outdated information as all current SSD drives will perform internal write-leveling (data relocation) in attempt to get around this. UFS also has one other benefit: it currently supports the "TRIM" operation (via BIO_DELETE) while ZFS doesn't. > 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? This all depends on how much swap and how often do you use it. I'd say it's a great idea if you run into out-of-memory situations rarely and then if you do run into it, you want the least performance degradation. In *all other cases* you will probably fry the SSD quickly. > another question i'd like to ask: are there also issues with read-cycles on > ssds? Not that I've heard of. > 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. It shouldn't - if the file system is mounted read-only then the underlying device will not be updated. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk8+c7wACgkQldnAQVacBcgAJgCg7w+pn8dAvmjg194jhb84cdeJ TzEAoNcGOmvffoWdUQMlNym11GJiIIvW =KDLy -----END PGP SIGNATURE-----home | help
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