Messages in this thread | | | From | Neil Brown <> | Date | Tue, 4 Jul 2006 17:02:13 +1000 | Subject | Re: ext4 features (checksums) |
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On Tuesday July 4, avi@argo.co.il wrote: > Neil Brown wrote: > > > > To my mind, the only thing you should put between the filesystem and > > the raw devices is RAID (real-raid - not raid0 or linear). > > > I believe that implementing RAID in the filesystem has many benefits too: > - multiple RAID levels: store metadata in triple-mirror RAID 1, random > write intensive data in RAID 1, bulk data in RAID 5/6 > - improved write throughput - since stripes can be variable size, any > large enough write fills a whole stripe
Maybe....
Now imagine what would be required to rebuild a whole drive onto a spare after a drive failure.
I'm sure it is possible, and I believe ZFS does something like that. I find it hard to imagine getting reasonable speed if there is much complexity. And the longer it takes, the longer your data is exposed to multiple-failures.
There may well be room there to come up with a really clever idea that makes it both flexible and fast....
Note that 'resync' wouldn't be a problem. Having the filesystem know about the raid means that resync (after unclean shutdown) can be quite trivial (I believe there is a paper related to this at OLS this year).
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