Messages in this thread | | | Date | Tue, 01 Apr 2008 10:02:40 +0200 | From | Tomasz Chmielewski <> | Subject | UBIFS vs Logfs (was [RFC PATCH] UBIFS - new flash file system) |
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Artem Bityutskiy wrote:
> I've renamed the thread because I do not like this flamish discussion > to me mixed with the technical one. > > Jörn Engel wrote: >> Shiny numbers! Performance has improved significantly in the last six >> month. Still worth a closer look. > We'll re-run them. Does logfs support write-back? Does it support compression?
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:
1. It works on normal block devices and it supports transparent compression
Today, a 64 GB SSD/flash-based media costs ~about the same as a 1 TB hard disk. This makes flash very expensive to use; compression can compensate that cost a bit (will depend on the usage, of course).
I believe there is no other Linux filesystem which can do transparent compression on block devices.
2. It does wear-levelling also on normal block devices
Although it doesn't sound normal to do wear-levelling twice (most flash-based block devices do wear-levelling on their own), I had a flash corruption after just ~one month of using RAID bitmap on a IDE-flash disk formatted with ext3. Apparently, device-level wear-levelling wasn't spreading updates of RAID bitmap file well enough.
(...)
> This basically means it is unfinished. Handling dynamic bad blocks is a *must* > if you are going to work on NAND, especially on MLC NAND which are not as > reliable as SLC. > I think you should bluntly say about this when you submit patches to prevent > people from starting using it in production.
I too wouldn't use LogFS today in a production environment - it is still not feature complete and not widely tested. I wouldn't use btrfs or ext4 today for the very same reason.
-- Tomasz Chmielewski http://wpkg.org
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