From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ptb-relay03.plus.net ([212.159.14.214]) by canuck.infradead.org with esmtps (Exim 4.42 #1 (Red Hat Linux)) id 1CfLF5-0006fP-W7 for linux-mtd@lists.infradead.org; Fri, 17 Dec 2004 11:46:13 -0500 From: "Gareth Bult (Encryptec)" To: Josh Boyer In-Reply-To: <41C3030D.8040607@us.ibm.com> References: <1103152743.15913.33.camel@squizzey.bult.co.uk> <41C0D3AC.3050801@us.ibm.com> <1103158974.15929.37.camel@squizzey.bult.co.uk> <1103201631.25765.7.camel@weaponx.rchland.ibm.com> <1103232128.15927.70.camel@squizzey.bult.co.uk> <41C1FDFF.3020308@us.ibm.com> <1103233669.15929.81.camel@squizzey.bult.co.uk> <1103288058.3018.4.camel@weaponx.rchland.ibm.com> <1103297611.15917.184.camel@squizzey.bult.co.uk> <41C3030D.8040607@us.ibm.com> Content-Type: text/plain Date: Fri, 17 Dec 2004 16:46:42 +0000 Message-Id: <1103302002.15927.198.camel@squizzey.bult.co.uk> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Cc: Linux MTD Subject: Re: JFFS2 mount time List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2004-12-17 at 10:02 -0600, Josh Boyer wrote: > For disk devices I don't think it's required, but it could help. Or > maybe your code does this at the MTD level. I dunno. I could be > spouting nonsense again ;). Mmm, as long as writes are aligned on 2k pages and are linear / unidirectional, I'm not sure anything else is really a problem for USB flash drives .. > Yes, it is a Journaled _Flash_ File System. So of course it's written > for MTD devices. Not sure why blkmtd.c was originally written. Test > vehicle for JFFS2, "why not", "I'm bored", etc. Who knows? :) Mm, my point exactly , Journaled _Flash_ File System - as opposed to Journaled _MTD_ _Flash_ File System .. !! USB flash is still flash! - just presented via a generic interface as opposed to an embedded one .. (AFAIK) I guess I was sort of hoping blkmtd.c was written to enable JFFS2 to be more generic and embedded device independent. I suspect however it was written purely for testing purposes .. :( As I understand it, the Flash in USB keys is identical to the MTD type embedded devices, except that the USB keys always come with micro-controllers that handle and optimise read/write/erase operations and present them via a generic PC/USB based disk interface. I'm not sure how fast MTD can be driven, but key manufacturers seem to think that keys should be able to run at 20Mb/sec read and 10Mb/sec write [for large block read/writes] which is much faster than is required for a key to replace a hard disk in a workstation. I'm thinking that JFFS2 could draw in a huge additional user base if it catered for (or at least supported) such devices .. (!) Gareth.