Hi,
I'm trying to troubleshoot an issue with a server; random writes are
way to slow.
I benchmarked two (different) servers with tiobench --size 100 and
this is what I got:
Server1 (6x10000rpm SCSI drives in RAID 5):
Sequential Writes
File Blk Num
Avg Maximum Lat% Lat% CPU
Identifier Size Size Thr Rate (CPU%)
Latency Latency >2s >10s Eff
---------------------------- ------ ----- --- ------ ------
--------- ----------- -------- -------- -----
2.6.14.3 100 4096 1 52.53 37.40%
0.020 10.73 0.00000 0.00000 140
2.6.14.3 100 4096 2 54.69 101.5%
0.028 8.06 0.00000 0.00000 54
2.6.14.3 100 4096 4 50.47 170.4%
0.051 104.07 0.00000 0.00000 30
2.6.14.3 100 4096 8 51.79 297.8%
0.046 127.94 0.00000 0.00000 17
Random Writes
File Blk Num
Avg Maximum Lat% Lat% CPU
Identifier Size Size Thr Rate (CPU%)
Latency Latency >2s >10s Eff
---------------------------- ------ ----- --- ------ ------
--------- ----------- -------- -------- -----
2.6.14.3 100 4096 1 10.78 6.900%
0.011 0.04 0.00000 0.00000 156
2.6.14.3 100 4096 2 9.13 13.55%
0.014 0.43 0.00000 0.00000 67
2.6.14.3 100 4096 4 8.78 18.87%
0.021 23.79 0.00000 0.00000 47
2.6.14.3 100 4096 8 8.77 26.93%
0.015 0.58 0.00000 0.00000 33
---
Server2 (2x7200rpm SATA drives in RAID 1 [md device]):
Sequential Writes
File Blk Num
Avg Maximum Lat% Lat% CPU
Identifier Size Size Thr Rate (CPU%)
Latency Latency >2s >10s Eff
---------------------------- ------ ----- --- ------ ------
--------- ----------- -------- -------- -----
2.6.14.3 100 4096 1 7.15
4.636% 0.020 11.14 0.00000 0.00000 154
2.6.14.3 100 4096 2 8.69
13.89% 0.025 56.36 0.00000 0.00000 62
2.6.14.3 100 4096 4 8.19
39.06% 0.041 63.43 0.00000 0.00000 21
2.6.14.3 100 4096 8 9.32
88.71% 0.097 171.91 0.00000 0.00000 11
Random Writes
File Blk Num
Avg Maximum Lat% Lat% CPU
Identifier Size Size Thr Rate (CPU%)
Latency Latency >2s >10s Eff
---------------------------- ------ ----- --- ------ ------
--------- ----------- -------- -------- -----
2.6.14.3 100 4096 1 0.39
0.169% 0.010 0.04 0.00000 0.00000 230
2.6.14.3 100 4096 2 0.29
0.298% 0.011 0.05 0.00000 0.00000 98
2.6.14.3 100 4096 4 0.32
0.927% 0.017 0.08 0.00000 0.00000 35
2.6.14.3 100 4096 8 0.36
1.184% 0.015 1.27 0.00000 0.00000 31
---
Factoring for RAID5, is this normal? Can I tune this somehow?
A.
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