On Wed, 2013-07-03 at 11:11 -0500, David Lehman wrote: > On Wed, 2013-07-03 at 17:31 +0200, Jan Safranek wrote: > > On 07/03/2013 05:08 PM, David Lehman wrote: > > > On Wed, 2013-07-03 at 10:34 +0200, Jan Safranek wrote: > > >> Hi, > > >> > > >> I noticed in F19 that blivet does not support RAID10 with 2 or 3 > > >> devices. What is the reason for this? Sure, RAID10 on 2 devices is equal > > >> to RAID1. But if you add new device to RAID1, you get more mirrors, > > >> while adding new device to RAID10 adds more space + speed. > > >> > > >> I am really not system admin, is this valid use case or not? > > > > > > I'm not a sysadmin either, nor am I a RAID expert, but my understanding > > > is that raid10 on <4 disks is actually RAID1E. Blivet doesn't support > > > RAID1E, regardless of what mdadm calls it. > > > > You are right, with three drives layout of data on RAID10 = RAID1E. With > > two drives, RAID10 = RAID1. But that's just coincidence, the data layout > > is same, but MD header is different and will behave differently when new > > drive is added. > > Blivet does not (and will not) aim to support every single configuration > allowed by, eg: mdadm. You can use some other means to create these > types of setups. If mdadm reports the array as usable, blivet will allow > you to use it. It just won't create such setups. I suppose this warrants some explanation. The reason for this is that all raid-like devices currently use the same code within blivet for determining minimum members, &c for a given raid level. As a result, the definitions have to be as standard as possible. At some point I may be able to find time to make something more flexible that would allow different definitions of a given raid level for different raid backends (eg: btrfs). Once such a framework is in place I could potentially start allowing things like mdadm raid10 with two or three members. Until then, it isn't really feasible. _______________________________________________ Anaconda-devel-list mailing list Anaconda-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/anaconda-devel-list
