IO testing, SSD versus SAS
The expected SSD performances are added below for guidance. The tests were performed by Bonnie++ using the same parameters for bo the SSD and SAS drives.
| Sequential Output | Sequential Input | Random Seeks |
Sequential Create | Random Create | ||||||||||||||||||||||
| IO Test |
Size:Chunk Size | Per Char | Block | Rewrite | Per Char | Block | Num Files | Create | Read | Delete | Create | Read | Delete | |||||||||||||
| K/sec | % CPU | K/sec | % CPU | K/sec | % CPU | K/sec | % CPU | K/sec | % CPU | / sec | % CPU | / sec | % CPU | / sec | % CPU | / sec | % CPU | / sec | % CPU | / sec | % CPU | / sec | % CPU | |||
| SAS unbuffered | 24008M | 65219 | 79 | 61731 | 8 | 38486 | 3 | 80270 | 97 | 102747 | 2 | 454.1 | 0 | 16 | 2741 | 2 | +++++ | +++ | 2464 | 2 | 2094 | 2 | +++++ | +++ | 2155 | 1 |
| SAS buffered | 24008M | 62152 | 75 | 70581 | 9 | 35703 | 2 | 79801 | 96 | 102588 | 2 | 404.9 | 0 | 16 | +++++ | +++ | +++++ | +++ | +++++ | +++ | +++++ | +++ | +++++ | +++ | +++++ | +++ |
| SSD unbuffered |
24008M | 84946 | 99 | 202446 | 29 | 96371 | 8 | 80093 | 97 | 241789 | 5 | 10776.6 | 24 | 16 | 3821 | 4 | +++++ | +++ | 3321 | 3 | 3665 | 4 | +++++ | +++ | 3361 | 2 |
| SSD buffered | 24008M | 78445 | 93 | 217912 | 30 | 95316 | 8 | 80561 | 97 | 239522 | 5 | 12778.4 | 30 | 16 | +++++ | +++ | +++++ | +++ | +++++ | +++ | +++++ | +++ | +++++ | +++ | +++++ | +++ |
SAS Technical specifications
Vendor technical sheets for the 3 Gb/sec SAS interface and the drive used (the Fujitsu MBC2073RC) indicates performance as below:
| FUNCTIONAL SPECIFICATIONS | |
| Formatted storage capacity | 73.5 GB |
| Seek time (track to track) | Read 0.2 / Write 0.4 ms. typ. |
| Seek time (average) | 3.0/3.5 ms. typ. (read/write) |
| Seek time (full track) | 6.0/7.0 ms. typ. (read/write) |
| Average latency time | 2.00 ms. |
| Rotational speed | 15,000 RPM |
| Interface | SAS (3Gbps) |
| Data Buffer Size | 16 MB |
| Recording code | 60/62 MEEPRML |
| Head positioning method | ROTARY VCM |
| Spindle start time | 15 seconds typical |
| Spindle stop time | 15 seconds typical |
None of the technical sheet would provide IO rates but only seek and access time latencies.
Pricing for a 73.5 GB, 15k RPM drive is ~ 160$ hence a cost of 2.2 $/GB.
SSD Technical specifications
The specifications for the Intel® X25-E Extreme SATA Solid-State Drive, a 64 GB are given on the Web and copied below.
|
Model name |
Intel® X25-E Extreme SATA Solid-State Drive |
|---|---|
|
Capacity |
32GB and 64GB |
|
NAND Flash components |
Intel® Single-Level Cell (SLC) NAND Flash Memory |
|
Bandwidth |
Sustained sequential read: up to 250 MB/s |
|
Read latency |
75 microseconds |
|
I/O Per Second (IOPS) |
Random 4KB Reads: >35,000 IOPS |
|
Interface |
SATA 1.5 Gb/s and 3.0 Gb/s |
|
Form factor |
2.5" by 7mm industry standard hard drive form factor |
|
Compatibility |
SATA Revision 2.6 Compliant. Compatible with SATA 3 Gb/s with Native Command Queuing and SATA 1.5 Gb/s interface rates |
|
Life expectancy |
2 Million Hours Mean Time Before Failure (MTBF) |
|
Power consumption |
Active: 2.4W Typical (server workload¹) |
|
Operating shock |
1,000G / 0.5ms |
|
Voltage |
5V SATA supply rail |
|
Operating temperature |
0°C to +70°C |
|
RoHS compliant |
Meets the requirements of EU RoHS Compliance Directives |
|
Product health monitoring |
Self-Monitoring, Analysis and Reporting Technology (S.M.A.R.T.) commands, plus additional SSD monitoring |
Pricing is given by the graph below - in green the lowest price found across all vendors and the blue, the median.
The price trend hence indicates a low is ~ 10 $/GB (pricing is a factor of ~ 5 comparing to a performing drive).
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