On Mar 27, 2010, at 5:07 AM, John R Pierce <pierce at hogranch.com> wrote: > Robert Spangler wrote: >> On Thursday 25 March 2010 18:10, Robert Heller wrote: >> >> >>> The prefered way to go would be RAID10 (RAID1 (mirror) + RAID0 >>> (stripe)). >>> Form pairs as RAID1, then strip the pairs. With 8 disks, this >>> would 4 >>> pairs, 1.5TB/pair = 1.5*4 = 6TB total. >>> >> >> I am just starting to look into this RAID and I was wondering >> wouldn't RAID01 >> be better then RAID10? In a 4 disc system having the first two using >> stripping and then backing them up the second set with mirrors? >> >> My though is having D1 and D2 as the primary drives stripping and >> then having >> D3 backup D1 and D4 backup D2. >> >> And if enough room place a couple more drives in the system as hot >> standby's. >> >> Or am I looking at this all wrong? >> > > > for all practical purposes its the same thing. if it was really > stripe then mirror, a naive mirror handler would think it would have > to > remirror both drives when one half of one of the stripesets failed and > was replaced. but in fact, the mirror handlres tend to be well > aware > of whats going on. mirror 0+1 aand stripe that with mirrored > 2+3, > and its really all the same the native raid10 in newer mdraid is > cleaner because you don't end up with extra partial volume > metadevices... RAID0+1 is never a good configuration because a single drive failure in a RAID0 stripe fails out the whole stripe, and with say an 4x2 RAID0+1, you are more likely to hit a disk failure with 4 drives in a RAID0 then 2 in a RAID1. That's why RAID1+0 came about. -Ross