Messages in this thread | | | Date | Tue, 1 Apr 2008 11:03:09 +0200 | From | Jörn Engel <> | Subject | Re: UBIFS vs Logfs (was [RFC PATCH] UBIFS - new flash file system) |
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On Tue, 1 April 2008 11:45:56 +0300, Artem Bityutskiy wrote: > Tomasz Chmielewski wrote: > >For me, the motivators to wait for LogFS are mainly the facts that it > >can work on traditional block devices, and not only on pure flash: > > Sorry Thomasz, for me this makes zero sense. There are _much_ better file > systems for block devices. UBIFS may work on top of a block device as > well (just needs few hacks to make it possible) - it is not a problem > at all, it is just _senseless_. > > JFFS2/UBIFS/LogFS is a separate _class_ of file-systems. The are designed > for _flash_, which has completely different work model then block device. > They are _native_ flash file systems. > Here are more details: > http://www.linux-mtd.infradead.org/faq/general.html#L_mtd_vs_hdd > > The traditional FSes _cannot_ work on top of flash. The solution for this > is using FTL, which emulates a block device on top of flash. It _hides_ the > real device, and fakes a block device for you. And you can use traditional > FSes on top of that fake block device. > > The whole _point_ of this separate class of FSes is because we believe > we may do much _better_ job if we use flash _natively_, instead of using > FTL. FTL is the place where you loose performance, reliability, and so on. > > And you are saying about using a native flash FS on top of a block device > like an SD card. This is just not sane: SD card first emulates a block > device > for you, looses performance at this point, then you again emulate a flash > on top of this, and suffer from this again.
About a year ago I would have used roughly the same argument. But in the meanwhile I have accepted the fact that any piece of flash I'll use in a notebook in the next five years will likely use SATA or USB as a transport medium.
Jörn
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