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Storage Spaces: Dual Redunancy?



 
 
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  #1  
Old October 22nd 16, 02:31 AM posted to alt.comp.os.windows-8
(PeteCresswell)
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Posts: 1,900
Default 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  
Old October 22nd 16, 06:23 AM posted to alt.comp.os.windows-8
Char Jackson
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Posts: 8,739
Default 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  
Old October 22nd 16, 08:51 AM posted to alt.comp.os.windows-8
Stephen Wolstenholme[_6_]
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Posts: 166
Default 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  
Old October 22nd 16, 03:12 PM posted to alt.comp.os.windows-8
Keith Nuttle
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Posts: 1,383
Default 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  
Old October 22nd 16, 03:27 PM posted to alt.comp.os.windows-8
(PeteCresswell)
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Posts: 1,900
Default 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  
Old October 24th 16, 04:24 PM posted to alt.comp.os.windows-8
Char Jackson
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Posts: 8,739
Default 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  
Old October 26th 16, 06:07 PM posted to alt.comp.os.windows-8
Char Jackson
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Posts: 8,739
Default 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  
Old October 26th 16, 07:30 PM posted to alt.comp.os.windows-8
Jonas Klein
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Posts: 30
Default 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  
Old October 27th 16, 06:42 PM posted to alt.comp.os.windows-8
Paul[_32_]
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Posts: 4,265
Default 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  
Old October 27th 16, 07:47 PM posted to alt.comp.os.windows-8
Jonas Klein
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Posts: 30
Default 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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