Re: [zfs-discuss] [RFC] Backup solution

2010-10-10 Thread Bob Friesenhahn
On Sat, 9 Oct 2010, Richard Elling wrote: On Oct 8, 2010, at 10:01 AM, Bob Friesenhahn wrote: Regardless, nothing beats raidz3 based on computable statistics. Well, no, not really. It all depends on the number of sets and the MTTR. Well, ok. I should have appended except for 3-way

Re: [zfs-discuss] [RFC] Backup solution

2010-10-09 Thread Richard Elling
On Oct 8, 2010, at 10:01 AM, Bob Friesenhahn wrote: Regardless, nothing beats raidz3 based on computable statistics. Well, no, not really. It all depends on the number of sets and the MTTR. Consider the case where you have 1 set of raidz3 and 2 sets of 3-way mirrors. The raidz3 set can only

Re: [zfs-discuss] [RFC] Backup solution

2010-10-08 Thread Edward Ned Harvey
From: Peter Jeremy [mailto:peter.jer...@alcatel-lucent.com] Sent: Thursday, October 07, 2010 10:02 PM On 2010-Oct-08 09:07:34 +0800, Edward Ned Harvey sh...@nedharvey.com wrote: If you're going raidz3, with 7 disks, then you might as well just make mirrors instead, and eliminate the slow

Re: [zfs-discuss] [RFC] Backup solution

2010-10-08 Thread Bob Friesenhahn
On Thu, 7 Oct 2010, Edward Ned Harvey wrote: If you're going raidz3, with 7 disks, then you might as well just make mirrors instead, and eliminate the slow resilver. While the math supports using raidz3, practicality (other than storage space) supports using mirrors. Mirrors are just much

Re: [zfs-discuss] [RFC] Backup solution

2010-10-08 Thread Michael DeMan
On Oct 8, 2010, at 4:33 AM, Edward Ned Harvey wrote: From: Peter Jeremy [mailto:peter.jer...@alcatel-lucent.com] Sent: Thursday, October 07, 2010 10:02 PM On 2010-Oct-08 09:07:34 +0800, Edward Ned Harvey sh...@nedharvey.com wrote: If you're going raidz3, with 7 disks, then you might as

Re: [zfs-discuss] [RFC] Backup solution

2010-10-08 Thread Bob Friesenhahn
On Fri, 8 Oct 2010, Michael DeMan wrote: Now, the above does not include things like proper statistics that the chances of that 2nd and 3rd disk failing (even correlations) may be higher than our 'flat-line' %/hr. based on 1-year MTBF, or stuff like if all the disks were purchased in the same

Re: [zfs-discuss] [RFC] Backup solution

2010-10-08 Thread Scott Meilicke
On Oct 8, 2010, at 8:25 AM, Bob Friesenhahn wrote: It also does not include the human factor which is still the most significant contributor to data loss. This is the most difficult factor to diminish. If the humans have difficulty understanding the system or the hardware, then they

Re: [zfs-discuss] [RFC] Backup solution

2010-10-08 Thread Roy Sigurd Karlsbakk
Now, the above does not include things like proper statistics that the chances of that 2nd and 3rd disk failing (even correlations) may be higher than our 'flat-line' %/hr. based on 1-year MTBF, or stuff like if all the disks were purchased in the same lots and at the same time, so their

Re: [zfs-discuss] [RFC] Backup solution

2010-10-08 Thread Bob Friesenhahn
On Fri, 8 Oct 2010, Roy Sigurd Karlsbakk wrote: In addition to this comes another aspect. What if one drive fails and you find bad data on another in the same VDEV while resilvering. This is quite common these days, and for mirrors, that will mean data loss unless you mirror 3-way or more,

Re: [zfs-discuss] [RFC] Backup solution

2010-10-08 Thread Edward Ned Harvey
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- boun...@opensolaris.org] On Behalf Of Roy Sigurd Karlsbakk In addition to this comes another aspect. What if one drive fails and you find bad data on another in the same VDEV while resilvering. This is quite common these days,

[zfs-discuss] [RFC] Backup solution

2010-10-07 Thread Roy Sigurd Karlsbakk
Hi all I'm setting up a couple of 110TB servers and I just want some feedback in case I have forgotten something. The servers (two of them) will, as of current plans, be using 11 VDEVs with 7 2TB WD Blacks each, with a couple of Crucial RealSSD 256GB SSDs for the L2ARC and another couple of

Re: [zfs-discuss] [RFC] Backup solution

2010-10-07 Thread Ian Collins
On 10/ 8/10 10:54 AM, Roy Sigurd Karlsbakk wrote: Hi all I'm setting up a couple of 110TB servers and I just want some feedback in case I have forgotten something. The servers (two of them) will, as of current plans, be using 11 VDEVs with 7 2TB WD Blacks each, with a couple of Crucial

Re: [zfs-discuss] [RFC] Backup solution

2010-10-07 Thread Roy Sigurd Karlsbakk
- Original Message - On 10/ 8/10 10:54 AM, Roy Sigurd Karlsbakk wrote: Hi all I'm setting up a couple of 110TB servers and I just want some feedback in case I have forgotten something. The servers (two of them) will, as of current plans, be using 11 VDEVs with 7 2TB WD

Re: [zfs-discuss] [RFC] Backup solution

2010-10-07 Thread Ian Collins
On 10/ 8/10 11:06 AM, Roy Sigurd Karlsbakk wrote: - Original Message - On 10/ 8/10 10:54 AM, Roy Sigurd Karlsbakk wrote: Hi all I'm setting up a couple of 110TB servers and I just want some feedback in case I have forgotten something. The servers (two of them) will, as of

Re: [zfs-discuss] [RFC] Backup solution

2010-10-07 Thread Scott Meilicke
Those must be pretty busy drives. I had a recent failure of a 1.5T disks in a 7 disk raidz2 vdev that took about 16 hours to resliver. There was very little IO on the array, and it had maybe 3.5T of data to resliver. On Oct 7, 2010, at 3:17 PM, Ian Collins wrote: I would seriously consider

Re: [zfs-discuss] [RFC] Backup solution

2010-10-07 Thread Ian Collins
On 10/ 8/10 11:22 AM, Scott Meilicke wrote: Those must be pretty busy drives. I had a recent failure of a 1.5T disks in a 7 disk raidz2 vdev that took about 16 hours to resliver. There was very little IO on the array, and it had maybe 3.5T of data to resliver. On Oct 7, 2010, at 3:17 PM, Ian

Re: [zfs-discuss] [RFC] Backup solution

2010-10-07 Thread Edward Ned Harvey
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- boun...@opensolaris.org] On Behalf Of Ian Collins I would seriously consider raidz3, given I typically see 80-100 hour resilver times for 500G drives in raidz2 vdevs. If you haven't already, If you're going raidz3, with 7

Re: [zfs-discuss] [RFC] Backup solution

2010-10-07 Thread Peter Jeremy
On 2010-Oct-08 09:07:34 +0800, Edward Ned Harvey sh...@nedharvey.com wrote: If you're going raidz3, with 7 disks, then you might as well just make mirrors instead, and eliminate the slow resilver. There is a difference in reliability: raidzN means _any_ N disks can fail, whereas mirror means one