Date: Fri, 25 Jul 2008 09:46:34 +0200 From: "Claus Guttesen" <kometen@gmail.com> To: "FreeBSD Stable" <freebsd-stable@freebsd.org> Subject: zfs, raidz, spare and jbod Message-ID: <b41c75520807250046y4ba061a2i63d3a40b7fc76170@mail.gmail.com>
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Hi. I installed FreeBSD 7 a few days ago and upgraded to the latest stable release using GENERIC kernel. I also added these entries to /boot/loader.conf: vm.kmem_size="1536M" vm.kmem_size_max="1536M" vfs.zfs.prefetch_disable=1 Initially prefetch was enabled and I would experience hangs but after disabling prefetch copying large amounts of data would go along without problems. To see if FreeBSD 8 (current) had better (copy) performance I upgraded to current as of yesterday. After upgrading and rebooting the server responded fine. The server is a supermicro with a quad-core harpertown e5405 with two internal sata-drives and 8 GB of ram. I installed an areca arc-1680 sas-controller and configured it in jbod-mode. I attached an external sas-cabinet with 16 sas-disks at 1 TB (931 binary GB). I created a raidz2 pool with 10 disks and added one spare. I copied approx. 1 TB of small files (each approx. 1 MB) and during the copy I simulated a disk-crash by pulling one of the disks out of the cabinet. Zfs did not activate the spare and the copying stopped until I rebooted after 5-10 minutes. When I performed a 'zpool status' the command would not complete. I did not see any messages in /var/log/message. State in top showed 'ufs-'. A similar test on solaris express developer edition b79 activated the spare after zfs tried to write to the missing disk enough times and then marked it as faulted. Has any one else tried to simulate a disk-crash in raidz(2) and succeeded? -- regards Claus When lenity and cruelty play for a kingdom, the gentlest gamester is the soonest winner. Shakespeare
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