| The target is running Debian Lenny 64bit userspace on an Intel Celeron 2.93GHz CPU, 2 GB RAM. |
| |
| Initiator is running Debian Etch 64 bit userspace, open-iscsi 2.0-869, Intel Xeon 3050/2.13GHz, 8 GB RAM. |
| |
| |
| Each test was repeated 6 times, "sync" was made and caches were dropped on both sides before each test was started. |
| |
| dd parameters were like below, so 6.6 GB of data was read each time: |
| |
| dd if=/dev/sdag of=/dev/null bs=64k count=100000 |
| |
| |
| Data was read from two block devices: |
| - /dev/md0, which is RAID-1 on two ST31500341AS 1.5 TB drives |
| - encrypted dm-crypt device which is on top of /dev/md0 |
| |
| Encrypted device was created with the following additional options passed to cryptsetup |
| (it provides the most performance on systems where CPU is a bottleneck, but with decreased |
| security when compared to default options): |
| |
| -c aes-ecb-plain -s 128 |
| |
| |
| Generally, CPU on the target was a bottleneck, so I also tested the load on target. |
| |
| |
| md0, crypt columns - averages from dd |
| us, sy, id, wa - averages from vmstat |
| |
| |
| 1. Disk speeds on the target |
| |
| Raw performance: 102.17 MB/s |
| Raw performance (encrypted): 50.21 MB/s |
| |
| |
| 2. Read-ahead on the initiator: 256 (default); md0, crypt - MB/s |
| |
| md0 us sy id wa | crypt us sy id wa |
| STGT 50.63 4% 45% 18% 33% | 32.52 3% 62% 16% 19% |
| SCST (debug + no patches) 43.75 0% 26% 30% 44% | 42.05 0% 84% 1% 15% |
| SCST (fullperf + patches) 45.18 0% 25% 33% 42% | 44.12 0% 81% 2% 17% |
| |
| |
| 3. Read-ahead on the initiator: 16384; md0, crypt - MB/s |
| |
| md0 us sy id wa | crypt us sy id wa |
| STGT 56.43 3% 55% 2% 40% | 46.90 3% 90% 3% 4% |
| SCST (debug + no patches) 73.85 0% 58% 1% 41% | 42.70 0% 85% 0% 15% |
| SCST (fullperf + patches) 76.27 0% 63% 1% 36% | 42.52 0% 85% 0% 15% |
| |
| Measured by Tomasz Chmielewski |
