Actually I found some time (and reason) to test this. Environment: - 1 osol server - one SLES10 iSCSI Target - two LUN's exported via iSCSi to the OSol server
I did some rescilver tests to see how ZFS resilvers devices. Prep: osol: create a pool (myiscsi) with one mirror pair made from the two iSCSI backend disks of SLES10 Test: osol: both disks ok, osol: txn in ueberblock of pool = 86 sles10: remove one disk (lun=1) osol: disk is detected failed, pool degraded osol: write with oflag=direct; sync multiple times to the pool osol: create fs myiscsi/test osol: txn in ueberblock = 107 osol: power off (hard) sles10: add lun 1 again (the one with txn 86) sles10: remove lun 0 (the onw with txn 107) osol: power on osol: txn in ueberblock = 92 osol: zfs myiscsi/test does not exist osol: create fs myiscsi/mytest_old osol: txn in ueberblock = 96 osol: power off (hard) sles10: add lun 0 again (with txn 107) sles10: both luns are there osol: Resilvering happens automatically osol: txn in ueberblock = 112 osol: filesystem myiscsi/test exists ... same thing other way around to see if rescilver direction is persistent ... osol: both disks ok, osol: txn in ueberblock = 120 sles10: remove one disk (lun=0) osol: write with oflag=sync; sync multiple times osol: create fs myiscsi/test osol: txn in ueberblock = 142 osol: power off (hard) sles10: add lun 0 again (the one with txn 120) sles10: remove lun 1 (the onw with txn 142) osol: boot osol: txn in ueberblock = 127 osol: filesystem myiscsi/test does not exist osol: create fs myiscsi/mytest_old osol: txn in ueberblock = 133 osol: power off sles10: add lun 1 again (with txn 142) sles10: both luns are there osol: boot osol: Resilvering happens automatically osol: txn in ueberblock = 148 osol: filesystem myiscsi/test exists --- >From this tests it seems that the latest txn always wins. This practially means that the jbod with most changes (in terms of transacitons) will always sync over the one with the least modifications. Could someone confirm this assumtion ? Could someone explain resilvering direction selection ? Regards, Robert p.s. I did not test split brain, but this is next. (The planned setup is clustered not iSCSI but SAS, so the split brain is more academic in this case). -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
