- CPU counters, the total used time (%USED) indicates system load, and ready time (%RDY)indicates overloaded CPU resources.
- A significant swap rate (SWW and SWR)in the memory counters is a clear indication of a shortage of ESX/ESXimemory,
- high device latencies (DAVG/cmd )in the storage section point to an overloaded or misconfigured array.
- Network traffic (MbRX MbTX) is not frequently the cause of most database performance problems except when large amounts of iSCSI storage traffic are using a single network line.
While pertaining to oracle databases, I thought this would be a good read for all databases.
This is my notes on the white paper
You can read the full thing here: http://www.vmware.com/files/pdf/partners/oracle/Oracle_Databases_on_VMware_-_Best_Practices_Guide.pdf
New issues –
Oracle Support reserves the right to ask customers to prove that “new issues” attributed to Oracle are not a result of an application being virtualized. This is reasonable, as this is essentially the same policy that other ISVs use to some degree. It is key to look at the history of Oracle Support with regard to new issues.
HOST
Recommendation Allow vSphere to choose the best virtual machine monitor based on the CPU
and guest operating system combination.
JustificationConfirm that the virtual machine setting has Automatic selected for the CPU/MMU Virtualization option.
Host Bios
Turbo Mode ::Yes ::Balanced workload over unused cores.
C1E Halt State ::No ::Disable if performance is more important than saving power.
Power-Saving ::No ::Disable if performance is more important than saving power.
Execute Disable:: Yes :: Required for vMotion and VMware vSphere Distributed Resource Scheduler (DRS) features.
Guest OS:
VMware recommends disabling unnecessary foreground and background processes within the guest operating system.
Examples of unnecessary Windows processes are: alerter, automatic updates, clip book, error reporting, help and support, indexing, messenger, netmeeting, remote desktop, and system restore services.
Virtual CPU
Recommendation Use as few virtual CPUs (vCPUs) as possible.
Justification If monitoring of the actual workload shows that the Oracle database is not benefitting from the increased virtual CPUs, the excess vCPUs impose scheduling
*Virtual machines with more than one virtual CPU are also called SMP (symmetric multiprocessing) virtual machines.
Cores vs hyperthreading:
Hyperthreading enables a single physical processor core to behave like two logical processors, allowing two independent threads to run simultaneously. Unlike having twice as many processor cores—which can roughly double performance—hyperthreading can provide anywhere from a slight to a significant increase in system performance by keeping the processor pipeline busier.
If the exact workload is not known, start with fewer virtual CPUs and increase the number later if necessary. Allocate multiple vCPUs to a virtual machine only if the anticipated database workload can take advantage of all the vCPUs.
*while this is standard practice, some DBA's might disagree on starting with lower vcpus so it’s a good line to show
Storage
Recommendation Create dedicated datastores to service database workloads.
The creation of dedicated datastores for I/O-intensive databases is Justification analogous to provisioning dedicated LUNs in the physical world. This is a typical design for a mission-critical enterprise workload.
Recommendation Use Paravirtualized SCSI adapters for Oracle data files with demanding workloads.
The combination of the new Paravirtualized SCSI driver (PVSCSI) and Justification additional ESX/ESXi kernel-level storage stack optimizations dramatically improves storage I/O performance.
During its testing, VMware has found that wire speed is the limiting factor for I/O throughput when comparing the storage protocols.
spread the database over multiple LUNs to maximize I/O performance (for example, placing log and datafiles in separate LUNs.
Storage Controllers
VMware highly recommends using multiple virtual SCSI controllers for the database virtual machines or virtual machines with high I/O load. The use of multiple virtual SCSI controllers allows the execution of several parallel I/O operations inside the guest operating system.
VMware also highly recommends separating the Redo/Log I/O traffic from the data file I/O traffic through separate virtual SCSI controllers. As a best practice, you can use one controller for the operating system and swap, another controller for DB Log, and one or more additional controllers for database data files
VMFS RDM
VMware is often asked which offers better performance, VMFS or RDM. Both VMFS and RDM volumes can provide similar transaction throughput.
VMware test results show that aligning VMFS
partitions to 64KB track boundaries results in reduced latency and increased throughput. VMFS
partitions created using vCenter are aligned on 64KB boundaries as recommended by storage and
operating
system vendors.
Alignment
It is considered a best practice to observe the following:
Create VMFS partitions from within vCenter because they are aligned by default.
Align the data disk [in windows[ for heavy I/O workloads using diskpart.
Paravirtualized SCSI Adapters
VMware recommends that you create a primary adapter for use with a disk that will host the system software (boot disk) and a separate PVSCSI adapter for the disk that will store the Oracle data files. Results of tests conclude that PVSCSI is not recommended for virtual machines performing less than 2,000 IOPS and issuing greater than four outstanding I/Os.
NIC
Take advantage of Network I/O Control to converge network and storage traffic onto 10GbE.
enables you to guarantee service levels (bandwidth) for particular vSphere traffic types: VM traffic, FT logging, iSCSI, NFS, management, and vMotion.
monitoring best practice.
Via esxtop
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