Performance Test: StorPool “SSD-Hybrid” shared storage system with 20x SSDs and 40x HDDs

This is a test of a StorPool Distributed Storage system, which we call “SSD-Hybrid”. It consists of 20 SSDs and 40 HDDs, spread evenly across 5 storage servers (nodes). The system uses 3 copies of each piece of data in a different server to guarantee redundancy (i.e. 3x replication). All reads and writes come/go the the SSDs first and are then replicated to 2 HDDs (Write-Back Cached) before committing an operation. Nevertheless this 100% cached storage system delivers indistinguishable all-flash performance, increased reliability at a very affordable price point.

Parameters of the system under test:

5 storage nodes, each with:
– Supermicro X10SRi-F server
– CPU: Intel Xeon E5-1620v4
– RAM: 4 x 8 GB DDR4 RDIMM @2133 MT/s
– NIC: 2-port Intel X520-2 (82599ES) 10GbE NIC
– HBA: Intel C610 AHCI – used for SSDs
– RAID controller: Supermicro AOC-S3108L-H8IR (Avago/LSI 3108 MegaRAID) w/CacheVault – used for HDDs
– 4x Samsung PM863a 1.92 TB
– 8x Seagate ST2000NM0135 2TB
– Linux kernel 2.6.32-642.11.1.el6.x86_64
– StorPool software version: 16.01.779

Total storage system resources:
– 5 storage nodes
– 10 x 10GE ports
– 20 x PM863a 1.92 TB SSDs, 40 x 2TB HDDs – 118 TB raw space, 34.9 TB usable space (before gains from space saving features)

– 2x 10GbE SFP+ switches
– Direct-attach SFP+ cables

– This test is performed with the workload and initiator software running on the same servers as the storage system. I.e. this configuration mimics a hyper-converged configuration
– There is no specific data affinity configured in this system. 1/5 of all IO happens to be on the same node as the initiator.

Measured total system throughput:
– Test was performed from all 5 server (client) hosts in parallel to show total system throughput
– Test performed on 5x 100 GiB fully allocated volumes
– Volumes were configured to “StorPool SSD-Hybrid” redundancy scheme, which stores 1 copy on SSDs and 2 copies on HDDs. It takes total approx 1.6 TB raw space (including copies and protection). This allocation policy provides maximum 32,511 GiB usable space from the available SSDs and HDDs
– Test was conducted with FIO 2.0.13, AIO, Direct on Linux block device


StorPool SSD-Hybrid IOPS

StorPool SSD-Hybrid MBs

Measured storage latency under different load levels:
– Test was performed from one initiator with different load levels, to show latency under load
– Queue depth starts from 1 and increased until latency goes above 1 ms
– At the high end of the queue depth scale, this test is limited by capability of the initiator, not by the whole storage system

StorPool Latency vs IOPS on SSD-HybridNote: When used from multiple initiators, this storage system can deliver even more random read+write 4k IOPS with sub-1 ms latency

StorPool SSD-Hybrid Latency

The total cost of this system as tested was approx $116,700 over 36 months (prices as of Jan 2017). This makes $3.3/GB usable and $0.19/IOPS. The system scales seamlessly and online with small steps.

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