ZFS: raid VS copies=n
Question: How does the ZFS option 'copies=n' and raid relate to and interact with each other? specifically recovery in the event of a failure. For example, is having three disks in a raid-1 configuration with copies=1 effectively the same as having three disks in a raid-0 with copies=3? Are the copies distributed uniformly across all drives in the pool, or concentrated, or what? What happens with configs like a raid-z2 with copies=2? Which / how many disks can you lose? (I'm aware that like a lot of other ZFS options copies=n doesn't have to be global to the entire pool / directory structure, but for the sake of simplicity let's assume it is in this case). __ it has a certain smooth-brained appeal ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: ZFS: raid VS copies=n
07.06.2013 18:52, Quartz: Question: How does the ZFS option 'copies=n' and raid relate to and interact with each other? specifically recovery in the event of a failure. For example, is having three disks in a raid-1 configuration with copies=1 effectively the same as having three disks in a raid-0 with copies=3? Are the copies distributed uniformly across all drives in the pool, or concentrated, or what? What happens with configs like a raid-z2 with copies=2? Which / how many disks can you lose? (I'm aware that like a lot of other ZFS options copies=n doesn't have to be global to the entire pool / directory structure, but for the sake of simplicity let's assume it is in this case). copies=n tries to allocate blocks on different disks but doesn't guarantee this nor that any single disk can be used to retrieve data. -- Sphinx of black quartz, judge my vow. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: ZFS: raid VS copies=n
In the last episode (Jun 07), Quartz said: How does the ZFS option 'copies=n' and raid relate to and interact with each other? specifically recovery in the event of a failure. For example, is having three disks in a raid-1 configuration with copies=1 effectively the same as having three disks in a raid-0 with copies=3? Are the copies distributed uniformly across all drives in the pool, or concentrated, or what? What happens with configs like a raid-z2 with copies=2? Which / how many disks can you lose? The code will try to place the extra copies on different vdevs, but if that's not possible, it will try and place them at least 1/8th of the disk size apart on the same disk. Copies aren't meant to protect against whole disk loss, but more local damage within a disk. https://blogs.oracle.com/bill/entry/ditto_blocks_the_amazing_tape https://blogs.oracle.com/relling/entry/zfs_copies_and_data_protection -- Dan Nelson dnel...@allantgroup.com ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
