Administrator Guide

Performance characterization
27 Dell EMC Ready Solution for HPC PixStor Storage | Document ID
mpirun --allow-run-as-root -np $Threads --hostfile my_hosts.$Threads --prefix
/mmfs1/perftest/ompi --mca btl_openib_allow_ib 1
/mmfs1/perftest/lanl_ior/bin/mdtest -v -d /mmfs1/perftest/ -i 1 -b $Directories
-z 1 -L -I 1024 -y -u -t -F -w 3K -e 3K
Figure 14 Metadata Performance - Small files (3K)
The system gets very good results for Stat and Read operations reaching their peak value at 256 threads with
8.29M op/s and 5.06M op/s respectively. Removal operations attained the maximum of 609K op/s at 128
threads and Create operations achieving their peak with 78K op/s at 512 threads. Stat and Read operations
have more variability than Create and Removal. Removal has a small drop in performance for the two higher
threads points suggesting the sustained performance after 128 threads will be slightly over 400K op/s.
Creates kept increasing up to 512 threads, but looks like is reaching a plateau so the maximum performance
may still be under 100K op/s.
Since small files like these are stored completely on the SSD based metadata module, applications requiring
superior small files performance, can use one or more optional high demand metadata modules to increase
small files performance. However, files that fit in the inode are tiny by current standards. Also, since the
metadata targets use RAID1s with SSDs relatively small (max size is 19.2TB), capacity will be limited when
compared to the storage nodes. Therefore, care must be exercised to avoid filling up Metadata targets, which
can cause unnecessary failures and other problems.
Summary
The current solution was able to deliver fairly good performance, which is expected to be stable regardless of
the used space (since the system was formatted in scattered mode), as can be seen in Table 5 MDtest
distribution of files on directories. Furthermore, the solution scales in capacity and performance linearly as
960
2,042
4,571
8,789
16,073
27,747
41,415
59,733
70,216
78,051
3,192
8,451
52,695
2,272,594
4,074,220
965,952
1,719,044
8,229,457
8,287,281
4,037,642
2,684
6,819
40,753
569,539
1,213,671
777,824
1,575,111
3,921,012
5,057,237
2,651,994
2,010
4,695
18,577
93,889
191,144
353,945
545,777
609,027
442,670
435,447
100
1000
10000
100000
1000000
10000000
1 2 4 8 16 32 64 128 256 512
IOPS
Threads
Metadata Performance (MDtest) - 3K Files
Create
Stat
Read
Removal