[LUDOC-154] Add wide striping content to Lustre manual (Ch 18)

• Type: Improvement
• Resolution: Fixed
• Priority: Major
• Labels: QContent
• Business Value: 6
• Assignee: Linda Bebernes (Inactive)
• Reporter: Brett Lee (Inactive)

Description

Cut/paste from Skype discussion with Andreas - 5/18/2013.

Brett Lee: wide striping requires a seperate inode for the EA that holds the ostnum:objectnum's?  does this mean that we cannot simply size a MDT by 2K inodes per file?  thanks.

Andreas Dilger: Brett: up to 160 stripes fit into a single 4kB block. beyond that, we allocate a new "xattr inode" to hold the xattr data. this needs to be enabled either at format time with "mkfs.lustre --mkfsoptions='-O large_xattr' ... /dev/

{mdsdev}" or afterward with "tune2fs -O large_xattr /dev/{mdsdev}

".

for wide striping the inode size isn't relevant, since it needs to be stored externally. now if every file had wide striping, then you would need to create fewer inodes (i.e. higher bytes per inode ratio) or the MDS would run out of space before inodes. that is very unlikely, however, so we don't consider this case by default