I have a Dell PERC H710P Raid Controller card and 4 Dell Certified 600GB Solid State Drives configured in RAID-10. I have a Dell Poweredge R820. After performing benchmark tests using ATTO, I usually average 3.5Gb/s speeds for read and write.
The machine is still fairly new, and does not have anything running on it yet. I noticed however, when I leave the server on and unattended (no programs running, machine is idle), the next day I go and perform the benchmark test again using ATTO, the read and write speeds decrease to 1 Gb/s.
Read Policy = Adaptive Read Ahead,
Write Policy = Write Back,
Stripe Element Size = 64KB,
Disk Cache Policy = Enabled,
The only solution I have found to restore the read and write speeds back 3.5 Gb/s is to restart the server.... everyday...
Any thoughts on why the read and write speeds decrease when the machine sits idle for over a day or so?
Answer
Check the power system profile in the BIOS and try setting it to 'Performance'. We've found a variety issues when the system is in power efficient mode. In addition to reduced storage i/o we've seen high latency on 10GbE networking and poor VM performance when the system is a hypervisor. But like your situation, the problems only manifest after the system has been running for a while.
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