On Sun, 17 Aug 2014 12:31:42 Duncan wrote: > OTOH, I tend to be rather more of an independent partition booster than > many. The biggest reason for that is the too many eggs in one basket > problem. Fully separate filesystems on separate partitions separate > those data "eggs" into separate baskets, so if the metaphorical bottom > drops out of one of those filesystem baskets, only the data eggs in that > filesystem basket are lost, while the eggs in the separate filesystem > baskets are still safe and sound, not affected at all. =:^) > > The thing that troubles me about replacing a bunch of independent > partitions and filesystems with a bunch of subvolumes on a single btrfs > filesystem is thus just that, you've nicely divided that big basket into > little subvolume compartments, but it's still one big basket, and if the > bottom falls out, you potentially lose EVERYTHING in that filesystem > basket!
I'll write the counter-point to this. If you have several partitions for /, /var/log, and /home then losing any one of them will result in a system that's mostly unusable. So for continuous service there doesn't seem to be a benefit in having multiple partitions. When you have to restore a backup in adverse circumstances the restore time is important. For example if you have 10*4TB disks and need RAID-1 redundancy (which you need on any BTRFS filesystem of note as I don't think RAID-5 and RAID-6 are trustworthy) then an advantage of 5*4TB RAID-1 filesystems over a 20TB RAID-10 is that restore time will be a lot smaller. But this isn't an issue for typical BTRFS users who are working with much smaller amounts of data, at this time I have to recommend ZFS over BTRFS for most systems that manage 20TB of data. If you have a RAID-1 array of the biggest disks available (which is probably the biggest storage for >99% of BTRFS users) then you are looking at a restore time of maybe 4TB at 160MB/s == something less than 7 hours. For a home network 7 hours delay in getting things going after a major failure is quite OK. Finally failures of filesystems on different partitions won't be independent. If one filesystem on a disk becomes unusable due to drive firmware issues or other serious problems then other filesystems on the same physical disk are likely to suffer the same fate. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/ -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
