raid10.. how many drives can fail and still have the array in tact?(4 drives/8 drives)

With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

Same with 8 drive?

Any thoughts?

Thanks

Previously markm75 wrote:
With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

A raid 10 uses RAID1 components as basis to build a RAID 0 on
top. If in any of the RAID1 subcomponents two drives fail, the
whole array fails.

For 4 drives that would be two RAID1 pairs. If 1 drive fails,
the array works. If 2 drives fail, it may or may not work.
3 drives kill oit reliably.


Same with 8 drive?

That would be 4 RAID1 pairs.

1 drive failure will not kill it. 2-4 drive failures may or may
not kill it, depending on whcih drives fail. 5 drives reliably
kill the array.

Arno

On Dec 20, 1:35 am, Arno Wagner wrote:
Previously markm75 wrote:
With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

A raid 10 uses RAID1 components as basis to build a RAID 0 on
top. If in any of the RAID1 subcomponents two drives fail, the
whole array fails.

For 4 drives that would be two RAID1 pairs. If 1 drive fails,
the array works. If 2 drives fail, it may or may not work.
3 drives kill oit reliably.

Same with 8 drive?

That would be 4 RAID1 pairs.

1 drive failure will not kill it. 2-4 drive failures may or may
not kill it, depending on whcih drives fail. 5 drives reliably
kill the array.

Arno

So basically with 4 drive.. there are two on each side.. if 1 drive on
one side dies.. its ok.. but if 1 drive on each side dies then its a
goner.. if 2 drives fail on one side.. i'd think it would be ok, just
not mirrored..

I'm trying to decide for my beefy virtual hosting server and file
server what to do.. i have 8, 500gb drives..

i originally was going to do 4 drive raid 5 for the main filesharing/
shares area.. then raid10 4 drive, for the virtual servers being
hosted on this box (8 of them, only 3 remotely beefy i guess).. i'd
prefer an all in one solution, but that would mean either going 8
drive raid5 (which would be horribly slow on rebuilds) or 8 drive
raid10, which sounds a little risky but fast on writes.

Previously markm75 wrote:
On Dec 20, 1:35 am, Arno Wagner wrote:
Previously markm75 wrote:
With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

A raid 10 uses RAID1 components as basis to build a RAID 0 on
top. If in any of the RAID1 subcomponents two drives fail, the
whole array fails.

For 4 drives that would be two RAID1 pairs. If 1 drive fails,
the array works. If 2 drives fail, it may or may not work.
3 drives kill oit reliably.

Same with 8 drive?

That would be 4 RAID1 pairs.

1 drive failure will not kill it. 2-4 drive failures may or may
not kill it, depending on whcih drives fail. 5 drives reliably
kill the array.

Arno

So basically with 4 drive.. there are two on each side.. if 1 drive on
one side dies.. its ok.. but if 1 drive on each side dies then its a
goner.. if 2 drives fail on one side.. i'd think it would be ok, just
not mirrored..

Exactly.

I'm trying to decide for my beefy virtual hosting server and file
server what to do.. i have 8, 500gb drives..

i originally was going to do 4 drive raid 5 for the main filesharing/
shares area.. then raid10 4 drive, for the virtual servers being
hosted on this box (8 of them, only 3 remotely beefy i guess).. i'd
prefer an all in one solution, but that would mean either going 8
drive raid5 (which would be horribly slow on rebuilds) or 8 drive
raid10, which sounds a little risky but fast on writes.

You should determine what your bottlenecks are first. You
may even have time for RAID6 without knowing it.

Arno

On Dec 20, 8:45 am, Arno Wagner wrote:
Previously markm75 wrote:
On Dec 20, 1:35 am, Arno Wagner wrote:
Previously markm75 wrote:
With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

A raid 10 uses RAID1 components as basis to build a RAID 0 on
top. If in any of the RAID1 subcomponents two drives fail, the
whole array fails.

For 4 drives that would be two RAID1 pairs. If 1 drive fails,
the array works. If 2 drives fail, it may or may not work.
3 drives kill oit reliably.

Same with 8 drive?

That would be 4 RAID1 pairs.

1 drive failure will not kill it. 2-4 drive failures may or may
not kill it, depending on whcih drives fail. 5 drives reliably
kill the array.

Arno
So basically with 4 drive.. there are two on each side.. if 1 drive on
one side dies.. its ok.. but if 1 drive on each side dies then its a
goner.. if 2 drives fail on one side.. i'd think it would be ok, just
not mirrored..

Exactly.

I'm trying to decide for my beefy virtual hosting server and file
server what to do.. i have 8, 500gb drives..
i originally was going to do 4 drive raid 5 for the main filesharing/
shares area.. then raid10 4 drive, for the virtual servers being
hosted on this box (8 of them, only 3 remotely beefy i guess).. i'd
prefer an all in one solution, but that would mean either going 8
drive raid5 (which would be horribly slow on rebuilds) or 8 drive
raid10, which sounds a little risky but fast on writes.

You should determine what your bottlenecks are first. You
may even have time for RAID6 without knowing it.

Arno- Hide quoted text -

- Show quoted text -

Hi there..

What did you mean by that ...(bottlenecks)..

RAID6.. how many drives can fail here.. is it the same as raid5.. i
have forgotten.. i think there was extra parity?

So raid6, 8 drives of 500gb.. does this still equate to 3.5TB?

I didnt think the writes were any better with raid6 than raid5.. i've
always been a fan of the writes of raid10.

On Dec 20, 8:45 am, Arno Wagner wrote:
Previously markm75 wrote:
On Dec 20, 1:35 am, Arno Wagner wrote:
Previously markm75 wrote:
With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

A raid 10 uses RAID1 components as basis to build a RAID 0 on
top. If in any of the RAID1 subcomponents two drives fail, the
whole array fails.

For 4 drives that would be two RAID1 pairs. If 1 drive fails,
the array works. If 2 drives fail, it may or may not work.
3 drives kill oit reliably.

Same with 8 drive?

That would be 4 RAID1 pairs.

1 drive failure will not kill it. 2-4 drive failures may or may
not kill it, depending on whcih drives fail. 5 drives reliably
kill the array.

Arno
So basically with 4 drive.. there are two on each side.. if 1 drive on
one side dies.. its ok.. but if 1 drive on each side dies then its a
goner.. if 2 drives fail on one side.. i'd think it would be ok, just
not mirrored..

Exactly.

I'm trying to decide for my beefy virtual hosting server and file
server what to do.. i have 8, 500gb drives..
i originally was going to do 4 drive raid 5 for the main filesharing/
shares area.. then raid10 4 drive, for the virtual servers being
hosted on this box (8 of them, only 3 remotely beefy i guess).. i'd
prefer an all in one solution, but that would mean either going 8
drive raid5 (which would be horribly slow on rebuilds) or 8 drive
raid10, which sounds a little risky but fast on writes.

You should determine what your bottlenecks are first. You
may even have time for RAID6 without knowing it.

Arno- Hide quoted text -

- Show quoted text -

btw.. it took 10hr 37 min for my 4 drive (500gb each) raid5 set to
build on this card.. and it took 1hr 41 min for the raid10 4 drive set
to build.

On Dec 20, 8:45 am, Arno Wagner wrote:
Previously markm75 wrote:
On Dec 20, 1:35 am, Arno Wagner wrote:
Previously markm75 wrote:
With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

A raid 10 uses RAID1 components as basis to build a RAID 0 on
top. If in any of the RAID1 subcomponents two drives fail, the
whole array fails.

For 4 drives that would be two RAID1 pairs. If 1 drive fails,
the array works. If 2 drives fail, it may or may not work.
3 drives kill oit reliably.

Same with 8 drive?

That would be 4 RAID1 pairs.

1 drive failure will not kill it. 2-4 drive failures may or may
not kill it, depending on whcih drives fail. 5 drives reliably
kill the array.

Arno
So basically with 4 drive.. there are two on each side.. if 1 drive on
one side dies.. its ok.. but if 1 drive on each side dies then its a
goner.. if 2 drives fail on one side.. i'd think it would be ok, just
not mirrored..

Exactly.

I'm trying to decide for my beefy virtual hosting server and file
server what to do.. i have 8, 500gb drives..
i originally was going to do 4 drive raid 5 for the main filesharing/
shares area.. then raid10 4 drive, for the virtual servers being
hosted on this box (8 of them, only 3 remotely beefy i guess).. i'd
prefer an all in one solution, but that would mean either going 8
drive raid5 (which would be horribly slow on rebuilds) or 8 drive
raid10, which sounds a little risky but fast on writes.

You should determine what your bottlenecks are first. You
may even have time for RAID6 without knowing it.

Arno- Hide quoted text -

- Show quoted text -

From looking at this description.. it would appear that all but one
drive can fail on each side and the array still works?
http://en.wikipedia.org/wiki/Nested_...els#RAID_1.2B0 (so 4 on
each side, 3 can fail on each side in raid10)?

On Dec 20, 8:45 am, Arno Wagner wrote:
Previously markm75 wrote:
On Dec 20, 1:35 am, Arno Wagner wrote:
Previously markm75 wrote:
With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

A raid 10 uses RAID1 components as basis to build a RAID 0 on
top. If in any of the RAID1 subcomponents two drives fail, the
whole array fails.

For 4 drives that would be two RAID1 pairs. If 1 drive fails,
the array works. If 2 drives fail, it may or may not work.
3 drives kill oit reliably.

Same with 8 drive?

That would be 4 RAID1 pairs.

1 drive failure will not kill it. 2-4 drive failures may or may
not kill it, depending on whcih drives fail. 5 drives reliably
kill the array.

Arno
So basically with 4 drive.. there are two on each side.. if 1 drive on
one side dies.. its ok.. but if 1 drive on each side dies then its a
goner.. if 2 drives fail on one side.. i'd think it would be ok, just
not mirrored..

Exactly.

I'm trying to decide for my beefy virtual hosting server and file
server what to do.. i have 8, 500gb drives..
i originally was going to do 4 drive raid 5 for the main filesharing/
shares area.. then raid10 4 drive, for the virtual servers being
hosted on this box (8 of them, only 3 remotely beefy i guess).. i'd
prefer an all in one solution, but that would mean either going 8
drive raid5 (which would be horribly slow on rebuilds) or 8 drive
raid10, which sounds a little risky but fast on writes.

You should determine what your bottlenecks are first. You
may even have time for RAID6 without knowing it.

Arno- Hide quoted text -

- Show quoted text -

Btw.. forgot.. that 10hr build time was a background build, not
foreground and the raid10 time was foreground only.

Previously markm75 wrote:
On Dec 20, 8:45 am, Arno Wagner wrote:
Previously markm75 wrote:
On Dec 20, 1:35 am, Arno Wagner wrote:
Previously markm75 wrote:
With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

A raid 10 uses RAID1 components as basis to build a RAID 0 on
top. If in any of the RAID1 subcomponents two drives fail, the
whole array fails.

For 4 drives that would be two RAID1 pairs. If 1 drive fails,
the array works. If 2 drives fail, it may or may not work.
3 drives kill oit reliably.

Same with 8 drive?

That would be 4 RAID1 pairs.

1 drive failure will not kill it. 2-4 drive failures may or may
not kill it, depending on whcih drives fail. 5 drives reliably
kill the array.

Arno
So basically with 4 drive.. there are two on each side.. if 1 drive on
one side dies.. its ok.. but if 1 drive on each side dies then its a
goner.. if 2 drives fail on one side.. i'd think it would be ok, just
not mirrored..

Exactly.

I'm trying to decide for my beefy virtual hosting server and file
server what to do.. i have 8, 500gb drives..
i originally was going to do 4 drive raid 5 for the main filesharing/
shares area.. then raid10 4 drive, for the virtual servers being
hosted on this box (8 of them, only 3 remotely beefy i guess).. i'd
prefer an all in one solution, but that would mean either going 8
drive raid5 (which would be horribly slow on rebuilds) or 8 drive
raid10, which sounds a little risky but fast on writes.

You should determine what your bottlenecks are first. You
may even have time for RAID6 without knowing it.

Arno- Hide quoted text -

- Show quoted text -

Hi there..

What did you mean by that ...(bottlenecks)..

Slowest components that matter.

RAID6.. how many drives can fail here.. is it the same as raid5.. i
have forgotten.. i think there was extra parity?

RAID6 can survive loss of any two disks. Since parity is
not enough, it will be slow with two failed drives.

So raid6, 8 drives of 500gb.. does this still equate to 3.5TB?

3TB.

I didnt think the writes were any better with raid6 than raid5.. i've
always been a fan of the writes of raid10.

RAID6 is about good redundancy.

Arno

Previously markm75 wrote:
On Dec 20, 8:45 am, Arno Wagner wrote:
Previously markm75 wrote:
On Dec 20, 1:35 am, Arno Wagner wrote:
Previously markm75 wrote:
With a 4 drive raid10.. i'm a little unclear on how many can fail here
and still work..

A raid 10 uses RAID1 components as basis to build a RAID 0 on
top. If in any of the RAID1 subcomponents two drives fail, the
whole array fails.

For 4 drives that would be two RAID1 pairs. If 1 drive fails,
the array works. If 2 drives fail, it may or may not work.
3 drives kill oit reliably.

Same with 8 drive?

That would be 4 RAID1 pairs.

1 drive failure will not kill it. 2-4 drive failures may or may
not kill it, depending on whcih drives fail. 5 drives reliably
kill the array.

Arno
So basically with 4 drive.. there are two on each side.. if 1 drive on
one side dies.. its ok.. but if 1 drive on each side dies then its a
goner.. if 2 drives fail on one side.. i'd think it would be ok, just
not mirrored..

Exactly.

I'm trying to decide for my beefy virtual hosting server and file
server what to do.. i have 8, 500gb drives..
i originally was going to do 4 drive raid 5 for the main filesharing/
shares area.. then raid10 4 drive, for the virtual servers being
hosted on this box (8 of them, only 3 remotely beefy i guess).. i'd
prefer an all in one solution, but that would mean either going 8
drive raid5 (which would be horribly slow on rebuilds) or 8 drive
raid10, which sounds a little risky but fast on writes.

You should determine what your bottlenecks are first. You
may even have time for RAID6 without knowing it.

Arno- Hide quoted text -

- Show quoted text -

btw.. it took 10hr 37 min for my 4 drive (500gb each) raid5 set to
build on this card.. and it took 1hr 41 min for the raid10 4 drive set
to build.

The RAID10 time is standard. The RAID5 time is extremely poor.
I have a 8 500GB disk software RAID6 on older hardware,
that builds in about 4 hours on Linux.

Arno