Re: Hints for ext3 filesystems on flash...
On Friday 10 April 2009 8:25:23 pm Martin Langhoff wrote: While I am not expecting the SD card to deal with a heavy write workload (the recommended strategy is to use an external disk for /var/lib and /library ), I am still keen on avoiding early SD card death... What about journal updates? Are you using an external journal and turning off access timestamp updates? Subbu ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Hints for ext3 filesystems on flash...
Hi Mitch, I'm working on getting bootable ext3 images to put on SD cards to use on the XO, to run the XS distro. While I am not expecting the SD card to deal with a heavy write workload (the recommended strategy is to use an external disk for /var/lib and /library ), I am still keen on avoiding early SD card death... Do we have any good rule of thumb on any partition alignment + blocksize that is likely to work well on current SD cards in the market? I've read your notes, and Tytso's blogposts about it; but maybe I'm not cultured enough to come up with a confident rule of thumb, and definitely have no idea whether it's possible to write a script to run on current linuxen that probes an SD card and Does The Right Thing. cheers, m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Hints for ext3 filesystems on flash...
Martin Langhoff wrote: Hi Mitch, I'm working on getting bootable ext3 images to put on SD cards to use on the XO, to run the XS distro. While I am not expecting the SD card to deal with a heavy write workload (the recommended strategy is to use an external disk for /var/lib and /library ), I am still keen on avoiding early SD card death... Do we have any good rule of thumb on any partition alignment + blocksize that is likely to work well on current SD cards in the market? A 1 MB granularity for partitions is likely to be adequate for now and the next couple of years. Ideally, it would be nice to work within the parameters of the factory partition map. Instead of just blasting on a new map with arbitrary layout, change only the partition type field, then dd the image into that partition. The image, of course, must be just the partition contents, not the whole disk. The partition-change thing could be scripted using fdisk or cfdisk. For the filesystem, I recommend a 4K blocksize. 2K was okay for the previous generation of NAND chips, but the new generation often uses 4K pages. I've read your notes, and Tytso's blogposts about it; but maybe I'm not cultured enough to come up with a confident rule of thumb, and definitely have no idea whether it's possible to write a script to run on current linuxen that probes an SD card and Does The Right Thing. cheers, m ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Fwd: Hints for ext3 filesystems on flash...
-- Forwarded message -- From: Tiago Marques tiago...@gmail.com Date: Fri, Apr 10, 2009 at 5:58 PM Subject: Re: Hints for ext3 filesystems on flash... To: Martin Langhoff martin.langh...@gmail.com On Fri, Apr 10, 2009 at 3:55 PM, Martin Langhoff martin.langh...@gmail.comwrote: Hi Mitch, I'm working on getting bootable ext3 images to put on SD cards to use on the XO, to run the XS distro. I've been doing these kinds of tests but using ext2, which has been working fine and should provide more durability. If you still want to go the ext3 route, take a look at this, if you haven't already: http://thunk.org/tytso/blog/2009/03/01/ssds-journaling-and-noatimerelatime/ I have had to have rootdelay=11 in olpc.fth, since my sdcard sometimes takes 10s to get detected instead of 0.5s or less, as usual. I'm using the kernel from OLPC's repositories, snapshot from last saturday. Best regards, Tiago Marques While I am not expecting the SD card to deal with a heavy write workload (the recommended strategy is to use an external disk for /var/lib and /library ), I am still keen on avoiding early SD card death... Do we have any good rule of thumb on any partition alignment + blocksize that is likely to work well on current SD cards in the market? I've read your notes, and Tytso's blogposts about it; but maybe I'm not cultured enough to come up with a confident rule of thumb, and definitely have no idea whether it's possible to write a script to run on current linuxen that probes an SD card and Does The Right Thing. cheers, m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel