raid10.. how many drives can fail and still have the array in tact? (4 drives/8 drives)
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From: markm75 on 19 Dec 2007 23:14 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
From: markm75 on 20 Dec 2007 08:22 On Dec 20, 1:35 am, Arno Wagner <m...(a)privacy.net> wrote: > Previously markm75 <markm...(a)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.
From: markm75 on 20 Dec 2007 09:30 On Dec 20, 8:45 am, Arno Wagner <m...(a)privacy.net> wrote: > Previously markm75 <markm...(a)msn.com> wrote: > > On Dec 20, 1:35 am, Arno Wagner <m...(a)privacy.net> wrote: > >> Previously markm75 <markm...(a)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.
From: markm75 on 20 Dec 2007 09:32 On Dec 20, 8:45 am, Arno Wagner <m...(a)privacy.net> wrote: > Previously markm75 <markm...(a)msn.com> wrote: > > On Dec 20, 1:35 am, Arno Wagner <m...(a)privacy.net> wrote: > >> Previously markm75 <markm...(a)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.
From: markm75 on 20 Dec 2007 09:41
On Dec 20, 8:45 am, Arno Wagner <m...(a)privacy.net> wrote: > Previously markm75 <markm...(a)msn.com> wrote: > > On Dec 20, 1:35 am, Arno Wagner <m...(a)privacy.net> wrote: > >> Previously markm75 <markm...(a)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_RAID_levels#RAID_1.2B0 (so 4 on each side, 3 can fail on each side in raid10)? |