On 8/2/06, John Hascall <[EMAIL PROTECTED]> wrote:
> In message <[EMAIL PROTECTED]>, John Hascall writes: > >The idea behind GFS is that these file chunks are > >stored on multiple (N, usually 3) chunkservers -- so > >you can lose N-1 of them and still be up and have > >your data. And the chunkservers could even be > and yet people still backup raid filesystems. there are certain > critical failures that cannot be solved with this solution. And which critical failures would that be?
BERs on modern storage devices are not decreasing anywhere near fast enough to counteract the rate of capacity increase. Data mirroring gives you error detection, not error correction (unless you set N=4, do quorum error resolution and assume simultaneous multi-disk failures will never happen). With the recent trends in storage device properties, simple mirroring is quickly becoming an unacceptable way of archiving data. Unless GFS is doing things like hierarchical checksumming, periodic checksum validation and disk surface scans, never overwriting live data (sounds like ZFS, huh?), you'll eventually wish you had backups. -- Tom Keiser [EMAIL PROTECTED] _______________________________________________ OpenAFS-devel mailing list [email protected] https://lists.openafs.org/mailman/listinfo/openafs-devel
