On Sat, 2008-07-19 at 15:21 +0300, Ahmed Kamal wrote: > Hi, > Since btrfs is someday going to be the default FS for Linux, and will > be on so many single disk PCs and laptops, I was thinking it should be > a good idea to insert some redundancy in single disk deployments. Of > course it can help with disk failures, since it's obviously a "single" > disk, but it can help with bit-rot, and with hardware sector read > errors. To get that we'd need to implement some kind of forward error > correction, possibly reed solomon code. I am not sure why no > filesystem seems to implement such scheme, although I believe at the > hardware level, such schemes are being used (so the idea is > applicable) ?
We have implementations of such schemes in lib/reed_solomon/ in the kernel already. I'm quite interested in using btrfs on flash (I mean _real_ flash not SSDs where they have their own internal pseudo-fs pretending to be a disk). For that, we'd probably want to use precisely this kind of error correction. Although it's normal to do it at the block level rather than the filesystem object level; I don't know if the failure modes on real disks are likely to be helped by this kind of scheme or not. After all, the disks already do a similar RS-based error correction for themselves. If we're unlucky in our choice of error correction, it might even be possible to end up in a situation where the only errors we'd _see_ are the ones which were uncorrectable. -- dwmw2 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
