I'm trying to figure out why the performance of a Virtual drive built from 12 SSDs is not really faster than a single SSD drive.
The Server is a IBM x3650 M4, two Xeon E5-2643v2 130W 6C 3,5GHz. The integrated RAID Controller ServerRAID M5110e has a BBU and 1GB Flash Option. Connected are 12 SSDs "IBM SSD S3500 240GB SATA 6,4cm MLC HS, 6.0 GB/s".
The RAID1 or RAID10 Virtual drives were created with the MegaRAID Storage Manager with the following properties: no read ahead, Write Back with BBU, Direct IO, 128k stripe size.
I tested the Performance with ATTO Disk Benchmark and here are the results of 64k read/writes (for other block size read/writes the Performance does not scale also):
2 drives in RAID1: Write 1969 MB/s Read 2458 MB/s 4 drives in RAID1: Write 1801 MB/s Read 2365 MB/s 6 drives in RAID1: Write 1614 MB/s Read 2381 MB/s 12 drives in RAID1: Write 1544 MB/s Read 2432 MB/s 12 drives in RAID10: Write 1738 MB/s Read 2465 MB/s
I've also ordered the IBM Option
"MegaRAID FastPath SSD performance acceleration MegaRAID FastPath software provides high-performance I/O acceleration for SSD-based virtual drives by exploiting an extremely low latency I/O path to increase the maximum I/O per second (IOPS) capability of the controller. This feature boosts the performance of applications with a highly random data storage access pattern, such as transactional databases. The feature is activated by enabling M5100 Series Performance Accelerator (90Y4273)."
But from what I understand this boosts the Performance of a Virtual Driver only by the factor of 2 or 3.
I'm wondering if the Controller is a bottleneck ?
I tested now with IOmeter with a 20 GB dataset, one worker, 64 KiB 100% Read, 0% random, running for five minutes:
RAID1 of 2 drives: Total IOPS 6917, Total MBPS 453 RAID1 of 4 drives: Total IOPS 9121, Total MBPS 597 RAID1 of 6 drives: Total IOPS 11186, Total MBPS 733 RAID1 of 8 drives: Total IOPS 12959, Total MBPS 850 RAID1 of 10 drives: Total IOPS 14677, Total MBPS 962 RAID1 of 12 drives: Total IOPS 16351, Total MBPS 1071 RAID10 of 12 drives: Total IOPS 18390, Total MBPS 1205 RAID0 of 6 drives: Total IOPS 16140, Total MBPS 1057 RAID0 of 12 drives: Total IOPS 19562, Total MBPS 1282 RAID5 of 12 drives: Total IOPS 18988, Total MBPS 1244 Tests with 50% reads, 50% writes: RAID5 of 12 drives: Total IOPS 4621, Total MBPS 303 RAID10 of 12 drives: Total IOPS 4967, Total MBPS 325 RAID10FP of 12 drives: Total IOPS 11803, Total MBPS 773
RAID10FP is the measurement when the purchased FastPath option is activated.