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#1
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Storage Spaces: Dual Redunancy?
I am trying to read
https://technet.microsoft.com/en-us/...(v=ws.11).aspx Under "Resilient storage", I see "Mirror. Writes data in a stripe across multiple disks while also writing one or two extra copies of the data. Use the mirror layout for most workloads – it helps protect your data from disk failures and provides great performance, especially when you add some SSDs to your storage pool and use storage tiers." Is this telling me what I hope it is: that I could set up a Storage Space across a dozen or so drives and have up to two drives fail without losing data? -- Pete Cresswell |
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#2
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Storage Spaces: Dual Redunancy?
On Fri, 21 Oct 2016 21:31:03 -0400, "(PeteCresswell)"
wrote: I am trying to read https://technet.microsoft.com/en-us/...(v=ws.11).aspx Under "Resilient storage", I see "Mirror. Writes data in a stripe across multiple disks while also writing one or two extra copies of the data. Use the mirror layout for most workloads – it helps protect your data from disk failures and provides great performance, especially when you add some SSDs to your storage pool and use storage tiers." Is this telling me what I hope it is: that I could set up a Storage Space across a dozen or so drives and have up to two drives fail without losing data? If that's what you're after, why not just use FlexRaid or SnapRaid? They do the same thing. |
#3
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Storage Spaces: Dual Redunancy?
On Fri, 21 Oct 2016 21:31:03 -0400, "(PeteCresswell)"
wrote: I am trying to read https://technet.microsoft.com/en-us/...(v=ws.11).aspx Under "Resilient storage", I see "Mirror. Writes data in a stripe across multiple disks while also writing one or two extra copies of the data. Use the mirror layout for most workloads – it helps protect your data from disk failures and provides great performance, especially when you add some SSDs to your storage pool and use storage tiers." Is this telling me what I hope it is: that I could set up a Storage Space across a dozen or so drives and have up to two drives fail without losing data? The mainframe computers I maintained had a resilient disc system like that. It never went wrong. That was about 20 years ago. Steve -- Neural Network Software for Windows http://www.npsnn.com |
#4
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Storage Spaces: Dual Redunancy?
On 10/21/2016 9:31 PM, (PeteCresswell) wrote:
I am trying to read https://technet.microsoft.com/en-us/...(v=ws.11).aspx Under "Resilient storage", I see "Mirror. Writes data in a stripe across multiple disks while also writing one or two extra copies of the data. Use the mirror layout for most workloads – it helps protect your data from disk failures and provides great performance, especially when you add some SSDs to your storage pool and use storage tiers." Is this telling me what I hope it is: that I could set up a Storage Space across a dozen or so drives and have up to two drives fail without losing data? Would this be the same as what we use to call it when we partitioned a disk. As I read it they are mirroring disk partition 1 (C) to disk partition 2 (D). With the size of disk today that would be a very affective way use of the disk. I have a 2TB disk on my desktop and a 500GB disk on my laptop that is synchronized to the desktop. I am using about 100GB of space on my laptop, so would have the same on the Desktop or about 100GB out on 2 TB of storage space, |
#5
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Storage Spaces: Dual Redunancy?
Per Char Jackson:
If that's what you're after, why not just use FlexRaid or SnapRaid? They do the same thing. I am currently using DriveBender. It got really flaky some months ago, so I re-built the system and changed over to an enclosure with backplanes and changed from multiple SATA cards to a single SAS card. So far, so good.... And the ability to yank a drive, put it in another machine, and have access to whatever files are on the drive has a certain appeal to me..... but I'm on my guard now and evaluating various alternatives if this build starts getting weird on me. My ignorance is huge in this area. Stumbled on Storage Spaces when trying to Google for alternatives.... Now that you have mentioned them, I need to look into FlexRaid and SnapRaid. The appeal there would be the possibility that I could implement one of them without rebuilding the existing Windows 7/purchasing Windows 8. Assuming both will run under Windows-7, do you prefer one over the other? -- Pete Cresswell |
#6
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Storage Spaces: Dual Redunancy?
On Sat, 22 Oct 2016 10:27:18 -0400, "(PeteCresswell)"
wrote: Per Char Jackson: If that's what you're after, why not just use FlexRaid or SnapRaid? They do the same thing. Now that you have mentioned them, I need to look into FlexRaid and SnapRaid. The appeal there would be the possibility that I could implement one of them without rebuilding the existing Windows 7/purchasing Windows 8. Right, at least for SnapRaid. I'm less familiar with the underpinnings of FlexRaid but I think it's true there, as well. Assuming both will run under Windows-7, do you prefer one over the other? I'm not using either of them, but I'm most interested in SnapRaid because its limited feature set doesn't overlap with DB. You can specify one or more drives to be your parity drives, with the only big requirement being that parity drives have to be as big as your biggest data drive, and you can decide how many drive failures you want to guard against by designating that number of parity drives. The two strikes against SnapRaid that I have a 1) I wouldn't want to run it against the DB volume directly, but rather against the individual drives that make up the DB volume. I assume that means that the individual drives need to have a drive letter assigned, which I don't normally do. This would apply equally to FlexRaid. 2) SnapRaid uses the snapshot model, so every night or so you'd run it and have it update the parity drives. If you lose one or more drives, up to the number of parity drives, you can recover to the state of the last snapshot. By contrast, I believe FlexRaid has a real-time capability, so that the parity drives are kept updated at all times. FlexRaid isn't free, though, and when I was more serious about it (2010 timeframe?) the author was prone to disappearing for months at a time. Both packages had good reviews, so it's mostly laziness that has kept me from taking the next step and picking one. It's 5-6 years later now, and I wonder if both are still being developed and supported. |
#7
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Storage Spaces: Dual Redunancy? (And request for RAID help)
On Wed, 26 Oct 2016 11:25:45 -0400, Wolf K wrote:
RAID is deigned to reduce the probability [of data loss] as close to zero as possible. With disks as cheap as they are now, I think RAID is ready for home and SOHO use. The first hurdle with RAID is convincing home users that RAID is not backup. I've run into that mindset more than a few times. |
#8
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Storage Spaces: Dual Redunancy? (And request for RAID help)
Am 26.10.2016 um 19:07 schrieb Char Jackson:
On Wed, 26 Oct 2016 11:25:45 -0400, Wolf K wrote: RAID is deigned to reduce the probability [of data loss] as close to zero as possible. With disks as cheap as they are now, I think RAID is ready for home and SOHO use. The first hurdle with RAID is convincing home users that RAID is not backup. I've run into that mindset more than a few times. Quite possible that a friend of mine made a fatal mistake or misunderstood RAID. Anyway, she told us that a failure in one component compromised all connected hard drives and computers. But the main purpose of RAID should be easy restoring of a compromised computer. Otherwise, it looks pretty nonsensical. Or I don't understand the idea behind it and what it's supposed to do. What I want and my friend wanted: an easy backup system that helps us save all data and restore the main computer when something goes wrong, whatever it is. |
#9
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Storage Spaces: Dual Redunancy? (And request for RAID help)
Wolf K wrote:
But RAID cannot restore a compromised computer. It merely stores two (or more) copies of the compromised system. NB that RAID does have error correction, so it helps reduce file corruption. But it can't protect against a compromised system, because that is not necessarily the same as file corruption. To restore a system, one either repairs it, or replaces it with an earlier, non-compromised version. That's why you need a back-up scheme. Have a good day, Actually, there is one more failure mechanism. Someone set up a RAID 1 mirror on a SIL3112. Then, one day, one of the disks died. On a mirror, the other disk immediately takes over and the user can continue to work. Well, on the SIL3112 in question, when the user examined the Downloads folder, the latest file on it was three months old. It turns out, the driver *stopped mirroring* three months before the failure! Three months worth of downloads, saved files, were missing. The only copy of them being on the dead hard drive. Both funny and tragic. The notion of a mirror that does not mirror. Who knew... And this is yet another reason, why your data should be backed up on an external drive, and kept well away from that "quality" RAID implementation. We had two RAID arrays at work, wiped out by a firmware bug on the $500 RAID card. In prime time, at 2PM in the afternoon in one of the cases. Again, RAID is sensitive to common-mode failures. The RAID controller card can ruin the array, as can the power supply, if the 12V rail shoots up to 15 volts and burns all the hard drive motors. When I mentioned the possibility of an ATX supply overshooting like that, someone posted in later in the day, to say that exact thing happened to them (ATX PSU ruins hard drives). Yes, you still want those backups. Paul |
#10
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Storage Spaces: Dual Redunancy? (And request for RAID help)
Am 27.10.2016 um 19:42 schrieb Paul:
Wolf K wrote: But RAID cannot restore a compromised computer. It merely stores two (or more) copies of the compromised system. NB that RAID does have error correction, so it helps reduce file corruption. But it can't protect against a compromised system, because that is not necessarily the same as file corruption. To restore a system, one either repairs it, or replaces it with an earlier, non-compromised version. That's why you need a back-up scheme. Have a good day, Actually, there is one more failure mechanism. Someone set up a RAID 1 mirror on a SIL3112. Then, one day, one of the disks died. On a mirror, the other disk immediately takes over and the user can continue to work. Well, on the SIL3112 in question, when the user examined the Downloads folder, the latest file on it was three months old. It turns out, the driver *stopped mirroring* three months before the failure! Three months worth of downloads, saved files, were missing. The only copy of them being on the dead hard drive. Both funny and tragic. The notion of a mirror that does not mirror. Who knew... My friend told me a sad story, you and Wolf disclosed other serious problems, so I have to confirm what I thought about RAID after her story: NIMO! (Not in my office!) Thank you for the confirmation. |
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