Hi. On Sat, Aug 10, 2019 at 05:25:30PM -0700, David Christensen wrote: > On 8/10/19 3:55 PM, Pascal Hambourg wrote: > > Le 10/08/2019 à 19:27, David Christensen a écrit : > > > On 8/10/19 4:35 AM, Andy Smith wrote: > > > > Personally I would use the three devices as a RAID-10 which would > > > > result in half the capacity of the total (768G) and you could > > > > withstand the loss of any one device. > > > > > > RAID 10 requires 4 drives: > > > > Not Linux implemention of RAID 10, which requires at least 2 drives. > > Do you have a URL or man page that describes this?
[1] says (emphasis mine): Raid 10 is a special linux mode which stores multiple copies of the data across several drives. There must be at least as many drives as there are copies - if the *two are equal* it is equivalent to raid-1. ... Conversion between raid-0 and raid-10 is supported - to convert to any other raid you will have to go via raid-0 - backup, BACKUP, BACKUP!!! The code does not appear to support conversion between raid-1 and raid-10 which should be easy for a *two-device* array. The big question is - why would anyone make a RAID10 consisting of two drives. It's impossible to reshape it (mdadm does not support it for RAID10), it's I/O characteristics are indistinguishable from RAID1. Reco https://raid.wiki.kernel.org/index.php/A_guide_to_mdadm#Raid_10
