On Mon, May 7, 2012 at 1:24 PM, Adrian Sevcenco <Adrian.Sevcenco at cern.ch> wrote: > On 05/02/12 18:47, Gianni Giardina wrote: >> >> Hi. >> The following HowTo on the CentOS Wiki: >> >> http://wiki.centos.org/HowTos/Install_On_Partitionable_RAID1 >> >> valid for CentOS 5, has not been updated to CentOS 6, yet. I found it >> very useful during the glorious CentOS 5 days and now that I've >> successfully ported my RAID1 experience to CentOS 6, I'd like to share >> it with the Community. > > > I have a question regarding partionable RAID : > why should the --metadata=0.90 be used? > in my man page (centos 6.2) i have this : > -e, --metadata= > Declare the style of RAID metadata (superblock) to be used. The default > is 1.2 for --create, and to guess for other operations. The default can be > overridden by setting the metadata value for the CREATE keyword in > mdadm.conf. > > Options are: > > 0, 0.90 Use the original 0.90 format superblock. This format limits > arrays to 28 component devices and limits component devices of levels 1 and > greater to 2 terabytes. It is also possible for there to be > confusion about whether the superblock applies to a whole device or just the > last partition, if that partition starts on a 64K boundary. > > 1, 1.0, 1.1, 1.2 default Use the new version-1 format superblock. This has > fewer restrictions. It can easily be moved between hosts with different > endian-ness, and a recovery operation can be checkpointed and restarted. > The different sub-versions store the superblock at different locations on > the device, either at the end (for 1.0), at the start (for 1.1) or 4K from > the start (for 1.2). "1" is equivalent to "1.2". "default" is equivalent to > "1.2". > > given the existence of 2+ tb hdd, metadata 0.9 is no go from the start ... > so, why 0.9 ? I always thought it was a huge advantage for software raid that the kernel would autodetect and assemble the components. Is there a way to make that happen with 1.x metadata? -- Les Mikesell lesmikesell at gmail.com