Re: [zfs-discuss] A question on non-consecutive disk failures
On Sun, Feb 8, 2009 at 1:56 AM, Peter Tribble peter.trib...@gmail.com wrote: snip/ No. That quote is part of the discussion of ditto blocks. See the following: http://blogs.sun.com/bill/entry/ditto_blocks_the_amazing_tape Thank you, Peter. -- Sriram ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] A question on non-consecutive disk failures
On Sun, Feb 8, 2009 at 1:29 AM, Frank Cusack fcus...@fcusack.com wrote: what mirror? there is no mirror. you have a raidz. you can have 1 disk failure. Thanks for the correction. I was thinking RAIDZ, but typed mirror. I have only RAIDZs on my servers. - if disks a and c fail, then I will be be able to read from disks b and d. Is this understanding correct ? no. you will lose all the data if 2 disks fail. The part of the slides you are referring to is in reference to ditto blocks, which allow failure of PARTS of a SINGLE disk. Thanks. I've started to read the various ZFS documentation. -- Sriram ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] A question on non-consecutive disk failures
Sriram, On Sun, Feb 08, 2009 at 12:04:22AM +0530, Sriram Narayanan wrote: From the presentation ZFS - The last word in filesystems, Page 22 In a multi-disk pool, ZFS survives any non-consecutive disk failures Questions: If I have a 3 disk RAIDZ with disks A, B and C, then: - if disk b fails, then will I be able to continue to read data if disks A and C are still available ? Yes, with RAIDZ, ZFS can sustain with 1 disk failure. If I have a 4 disk RAIDZ with disks A, B, C, and D, then: - if disks a and b fail, then I won't be able to read from the mirror any more. Is this understanding correct ? Since, this is a RAIDZ configuration, it can sustain upto one disk failure. So, answer is no. RAIDZ is similar to RAID-5 wrt to redundancy. - if disks a and c fail, then I will be be able to read from disks b and d. Is this understanding correct ? Same as above. However, if you had configured it as RAIDZ-2 then it can sustain upto 2 disk failures. The other option would be configure it as mirrored pool. And this too can sustain 2 disk failures (one in each mirror device). Hope that helps. Thanks and regards, Sanjeev -- Sriram ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] A question on non-consecutive disk failures
From the presentation ZFS - The last word in filesystems, Page 22 In a multi-disk pool, ZFS survives any non-consecutive disk failures Questions: If I have a 3 disk RAIDZ with disks A, B and C, then: - if disk b fails, then will I be able to continue to read data if disks A and C are still available ? If I have a 4 disk RAIDZ with disks A, B, C, and D, then: - if disks a and b fail, then I won't be able to read from the mirror any more. Is this understanding correct ? - if disks a and c fail, then I will be be able to read from disks b and d. Is this understanding correct ? -- Sriram ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] A question on non-consecutive disk failures
On February 8, 2009 12:04:22 AM +0530 Sriram Narayanan sri...@belenix.org wrote: From the presentation ZFS - The last word in filesystems, Page 22 In a multi-disk pool, ZFS survives any non-consecutive disk failures Questions: If I have a 3 disk RAIDZ with disks A, B and C, then: - if disk b fails, then will I be able to continue to read data if disks A and C are still available ? yes. raidz allows for 1 disk failure. If I have a 4 disk RAIDZ with disks A, B, C, and D, then: - if disks a and b fail, then I won't be able to read from the mirror any more. Is this understanding correct ? what mirror? there is no mirror. you have a raidz. you can have 1 disk failure. - if disks a and c fail, then I will be be able to read from disks b and d. Is this understanding correct ? no. you will lose all the data if 2 disks fail. The part of the slides you are referring to is in reference to ditto blocks, which allow failure of PARTS of a SINGLE disk. -frank ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] A question on non-consecutive disk failures
On Sat, Feb 7, 2009 at 6:34 PM, Sriram Narayanan sri...@belenix.org wrote: From the presentation ZFS - The last word in filesystems, Page 22 In a multi-disk pool, ZFS survives any non-consecutive disk failures Questions: If I have a 3 disk RAIDZ with disks A, B and C, then: - if disk b fails, then will I be able to continue to read data if disks A and C are still available ? If I have a 4 disk RAIDZ with disks A, B, C, and D, then: - if disks a and b fail, then I won't be able to read from the mirror any more. Is this understanding correct ? - if disks a and c fail, then I will be be able to read from disks b and d. Is this understanding correct ? No. That quote is part of the discussion of ditto blocks. See the following: http://blogs.sun.com/bill/entry/ditto_blocks_the_amazing_tape -- -Peter Tribble http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/ ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
