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 <markm75c@msn.com> 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 <m...@privacy.net> wrote:
> Previously markm75 <markm...@msn.com> 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 <markm75c@msn.com> wrote:
> On Dec 20, 1:35 am, Arno Wagner <m...@privacy.net> wrote:
>> Previously markm75 <markm...@msn.com> 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 <m...@privacy.net> wrote:
> Previously markm75 <markm...@msn.com> wrote:
> > On Dec 20, 1:35 am, Arno Wagner <m...@privacy.net> wrote:
> >> Previously markm75 <markm...@msn.com> 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 <m...@privacy.net> wrote:
> Previously markm75 <markm...@msn.com> wrote:
> > On Dec 20, 1:35 am, Arno Wagner <m...@privacy.net> wrote:
> >> Previously markm75 <markm...@msn.com> 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 <m...@privacy.net> wrote:
> Previously markm75 <markm...@msn.com> wrote:
> > On Dec 20, 1:35 am, Arno Wagner <m...@privacy.net> wrote:
> >> Previously markm75 <markm...@msn.com> 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 <m...@privacy.net> wrote:
> Previously markm75 <markm...@msn.com> wrote:
> > On Dec 20, 1:35 am, Arno Wagner <m...@privacy.net> wrote:
> >> Previously markm75 <markm...@msn.com> 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 <markm75c@msn.com> wrote:
> On Dec 20, 8:45 am, Arno Wagner <m...@privacy.net> wrote:
>> Previously markm75 <markm...@msn.com> wrote:
>> > On Dec 20, 1:35 am, Arno Wagner <m...@privacy.net> wrote:
>> >> Previously markm75 <markm...@msn.com> 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 <markm75c@msn.com> wrote:
> On Dec 20, 8:45 am, Arno Wagner <m...@privacy.net> wrote:
>> Previously markm75 <markm...@msn.com> wrote:
>> > On Dec 20, 1:35 am, Arno Wagner <m...@privacy.net> wrote:
>> >> Previously markm75 <markm...@msn.com> 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