Administrator Guide

Performance characterization
26 Dell EMC Ready Solution for HPC PixStor Storage | Document ID
Figure 13 Metadata Performance - Small files (4K)
The system gets very good results for Stat and Removal operations reaching their peak value at 128 threads
with 7.7M op/s and 1M op/s respectively. Removal operations attained the maximum of 37.3K op/s and
Create operations achieving their peak with 55.5K op/s, both at 512 threads. Stat and Removal operations
have more variability, but once they reach their peak value, performance does not drop below 4M op/s for
Stats and 200K op/s for Removal. Create and Read have less variability and keep increasing as the number
of threads grows.
Since these numbers are for a metadata module with a single ME4024, performance will increase for each
additional ME4024 arrays, however we cannot just assume a linear increase for each operation. Unless the
whole file fits inside the inode for such file, data targets on the ME4084s will be used to store the 4K files,
limiting the performance to some degree. Since the inode size is 4KiB and it still needs to store metadata,
only files around 3 KiB will fit inside and any file bigger than that will use data targets.
Metadata Performance using MDtest with 3K files
This test is almost exactly identical to the previous ones, except that small files of 3KiB were used. The main
difference is that these files fit completely inside the inode. Therefore, the storage nodes and their ME4084s
are not used, improving the overall speed by using only SSD media for storage and less network accesses.
The following command was used to execute the benchmark, where Threads was the variable with the
number of threads used (1 to 512 incremented in powers of two), and my_hosts.$Threads is the
corresponding file that allocated each thread on a different node, using round robin to spread them
homogeneously across the 16 compute nodes.
653
1,397
3,044
6,362
12,977
23,923
34,892
43,825
47,846
55,465
2,698
13,283
466,991
2,069,061
4,041,627
6,345,515
4,211,455
7,735,138
6,836,957
6,769,751
197
434
869
2,302
6,300
7,227
12,102
16,696
27,294
37,304
2,230
9,435
44,071
108,196
238,374
219,523
499,627
1,004,137
767,809
322,215
100
1000
10000
100000
1000000
10000000
1 2 4 8 16 32 64 128 256 512
IOPS
Threads
Metadata Performance (MDtest) - 4K Files
Create
Stat
Read
Removal