Date: Tue, 23 Jun 2009 20:22:25 +0200 From: Roland Smith <rsmith@xs4all.nl> To: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> Cc: Gary Kline <kline@thought.org>, FreeBSD Mailing List <freebsd-questions@freebsd.org> Subject: Re: you're not going to believe this. Message-ID: <20090623182225.GC33220@slackbox.xs4all.nl> In-Reply-To: <alpine.BSF.2.00.0906231922250.58723@wojtek.tensor.gdynia.pl> References: <20090622230729.GA20167@thought.org> <alpine.BSF.2.00.0906230929470.55064@wojtek.tensor.gdynia.pl> <20090623170739.GA33220@slackbox.xs4all.nl> <alpine.BSF.2.00.0906231922250.58723@wojtek.tensor.gdynia.pl>
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--/e2eDi0V/xtL+Mc8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jun 23, 2009 at 07:23:22PM +0200, Wojciech Puchar wrote: > >> whatever. > > > > Not so. See http://en.wikipedia.org/wiki/Flash_file_system > > > > Most flash devices sold as harddisks have hardware that emulates a > > traditional harddisk, representing it as a (P/S)ATA block device. Unless > > you can bypass this, there is no need for a special filesystem. >=20 > yes this is exactly a problem. it emulates hard disk, which lowers=20 > performance much. for example wear leveling and emulation small=20 > blocks requires moving of data within flash, this lowers both performance= =20 > and lifetime. Even a flash filesystem will have to do wear levelling. And you'll have to gather writes to minimize the (slow) wiping of eraseblocks. In other words, you'll be doing more or less the same that current hardware does. But then in software, which is generally slower than dedicated hardware. The big difference is that it is much easier to tweak and change algorithms when doing it in software. Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --/e2eDi0V/xtL+Mc8 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.12 (FreeBSD) iEYEARECAAYFAkpBHWEACgkQEnfvsMMhpyU/dQCfaVbYL7nJBq8tRMqEwhRcGg2x UTEAoJ0CDJfiLZZp3FVNaDg5wSggYg62 =Pqhb -----END PGP SIGNATURE----- --/e2eDi0V/xtL+Mc8--
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