I used to see memory degrading on Cisco UCS blades. But less see on HPE blades. I thought it maybe quality control problem of Cisco manufacture. Today I read two articles in Cisco website, it explains why we see memory degrading and how it works. I attached the articles below.
Managing Correctable Memory Errors on Cisco UCS Servers
UCS Enhanced Memory Error Management
The conduction in the whitepaper is not only specific for Cisco UCS, but also for any modern servers. Following is summary of why memory errors rates is going high nowadays.
- Larger memory systems contain more bits
- Higher capacity DRAM chips require smaller bit cells which result in fewer stored charges per bit
- Lower operating voltages can lead to reduced noise margin
- Higher operating speeds can lead to reduced timing margin
DBA team told me Oracle was running slow on a HPE server. I observed the CPU utilization was about 50% of overall capacity. Whenever Oracle database bumps up the system experienced slowness.
Further digged into the issue, I see Oracle workload only ran on single physical processor, but the server has two processors. And the Windows 2012 R2 resource manager show the system used Processor Group, the two physical processors were grouped out. This technology is described in Microsoft MSDN article.
To fix the issue you have to change value of “NUMA Group Size Optimization” to “Flat” in BIOS. Please refer to HPE article for detail steps.
Detail of HPE server behavior is documented here. Please note, the article says it impacts to ProLiant Gen9 and Intel E5-26xx v3 processors. But it actually also impacts to Intel E5-26xx v4 and Synergy blades.
DHCP uses UDP as its transport protocol. DHCP messages from a client
to a server are sent to the ‘DHCP server’ port (67), and DHCP
messages from a server to a client are sent to the ‘DHCP client’ port
(68). A server with multiple network address (e.g., a multi-homed
host) MAY use any of its network addresses in outgoing DHCP messages.
使用vSphere Client登录vCenter Server 6.0时可能会出现如下报错信息：
Login to the query service failed.
The server could not interpret the communication from the client. (The remote server returned an error: (500) Internal Server Error.)
这是因为在登录vSphere Client时勾选了”Use Windows session credentials“。试试取消它。
相关知识库链接：Searching the Inventory with the vSphere Client fails (2143566)