SingleShared File performance MRP862 Nathan Rutman nathanrutmanxyratex com

Single-Shared File performance MRP-862 Nathan Rutman (nathan_rutman@xyratex. com)

SSF ● ● Multiple clients write to multiple ranges within the same file Scientific apps mostly - simulations Wide striping Different than FPP o o o Locking model Readahead Stripe alignment

IOR and Lustre terms Block. Size process 1 Block. Size Transfer. Size IOR Single Shared File process 2 process 3 process 11 process 2 process 3 Segment 1 Segment 2 stride Stripe. Size Stripe Count stripe 1 stripe 2 stripe 3 stripe 4 Lustre data layout Stripe. Size = 1 MB default

IOR - misaligned blocksize Transfer. Size Block. Size process 2 process 3 process 11 process 2 process 3 Segment 1 Stripe. Size Transfer. Size Stripe Count Transfer. Size Stripe. Size Transfer. Size extra, small bulk RPCs Segment 2 Stripe. Size process 1 Transfer. Size Block. Size Transfer. Size IOR Single Shared File stripe 1 stripe 2 stripe 3 stripe 4 Lustre data layout LDLM lock splitting drive head contention

IOR - small blocksize Block. Size Block. Size Transfer. Size Block. Size IOR Single Shared File proc proc proc proc 1 2 proc 3 24 proc 5 36 proc 7 48 Segment 1 Segment 2 Stripe Count Stripe. Size Stripe. Size LDLM lock splitting drive contention stripe 1 stripe 2 stripe 3 stripe 4 Lustre data layout

IOR - large blocksize Block. Size process 1 Block. Size Transfer. Size IOR Single Shared File process 2 process 3 process 4 Segment 1 Stripe Count Stripe. Size drive contention Stripe. Size Transfer. Size Stripe Count stripe 1 stripe 2 stripe 3 stripe 4 Lustre data layout

IOR - ideal Block. Size proc 2 proc 3 proc 4 proc 1 proc 2 proc 3 proc 4 Stripe. Size Stripe Count Stripe. Size Segment 2 Stripe. Size Segment 1 Stripe. Size Block. Size proc 1 Transfer. Size Stripe. Size Transfer. Size Block. Size Transfer. Size IOR Single Shared File stripe 1 stripe 2 stripe 3 stripe 4 Lustre data layout