Thursday Apr 10, 2014

Working with SCAN on Exalogic

During this last time, I have seen more Exalogic customers using SCAN, so decided to write a brief article about it, although there is a lot of documentation from Oracle about it.

Single Client Access Name (SCAN) is a JDBC driver feature that provides a single name for clients to access any Oracle Database running in a cluster. Some of its benefits and advantages include:
- Client’s connect information does not need to change if you add or remove nodes or databases in the cluster
- Fast Connection Failover (FCF)
- Runtime Connection Load-Balancing (RCLB)
- Can be implemented with MultiDataSource or GridLink
- It can also be used with Oracle JDBC 11g Thin Driver (this is clearly explained on MOS note 1290193.1)

In the particular case of Exalogic, a typical architecture, widely used by customers, is to having it connected to an Exadata (which hosts the database) machine through InfiniBand. Obviously the SCAN feature can be used within this Engineered Systems architecture. As a matter of fact, GridLink is part of the Exalogic-Specific enhancements of Weblogic.

Some facts to keep in mind when using it:
- SCAN feature is supported on JDBC version 11.2.0.1 and above
- Just as any situation when a connection to database is involved, need to be careful that firewalls may cause some network adapter or timeout issues, which must be solved so the connection can be established
- If using VIP hosts, instead of cluster configuration having the short host name for the VIP hosts, you should set LOCAL_LISTENER to the fully qualified domain name (e.g. node-VIP.example.com):
(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=node-VIP.example.com)(PORT=1521))))

Wednesday Aug 21, 2013

Resource allocation on vServers

A few facts to keep in mind.

The number of vCPUs to existent vServer cannot be modified. Currently vDC resource management (changing vCPU, memory, etc.) after a vServer has been created is not supported in Exalogic Virtual environments. However, a customer vServer type with required memory can be created and used instead of the default VM types.

Note that the Server pool management is handled by Exalogic, manual management of it is not available. Also, keep in mind that there is no way to control which physical host is assigned a given vServer. The scheduler algorithms are sophisticated but it is fine-grained and there is no reason to assume that the scheduler will not be maximally efficient. EMOC will look at the resources allocated to the vServer that is being planned on creating (CPUs/memory), then look at what is available on each of the compute nodes and make a decision on where to place the vServer. System administrators can try to use Distribution groups and separate the vServers they have to run across different Oracle VM Servers.

If need to increase Root File System and Swap Space of an Exalogic Guest Virtual Machine, then the MOS Note 1575790.1 is useful for that purpose.

Thursday Jun 20, 2013

Exachk 2.2.2 released - Now Includes Support for Exalogic Solaris Environments

This new Exachk 2.2.2 release includes several new improvements and features.

The following are additional checks as part of this new 2.2.2 release for Solaris:
Compute Nodes
- Hardware and Firmware Profile
- Software Profile
- NTP Synchronization
- DNS Setup
- Correct Slot Installation of IB Card for Solaris
- Subnet Manager
- Root Partition Usage Limit for Solaris
- Lockd Configuration for Solaris Compute Node
- ib_ipoib Module for Solaris
- ib_sdp Module for Solaris
- IP Configuration - net0 and bond0
- Recent Reboot Info for Solaris
- Probe Based IPMP for Solaris
- Swap Space for Solaris
- Free Physical Memory for Solaris
- MTU for Solaris
- IPMP Configuration for Solaris
- Fault Management Log for Solaris
- BIOS Settings
- NFS Mount Point - Version for Solaris
- Hostname Consistency with DNS on the Physical Compute Node
- NFS Mount Point - Attribute Caching for Solaris
- NFS Mount Point - Rsize Wsize for Solaris
- NIS domain (YPBind) for Solaris

Also, the following checks have been enhanced as part of this new 2.2.2 release:
Compute Nodes
- Connectivity To OVMM
- MTU Value for Infiniband Interface
- Hostname Matches the DNS on the Physical Compute Node
Switch
- Non-sequential Even-numbered Gateway Instance
Cross-Components
- NTP Configuration for Switch Nodes Matches Physical Compute Nodes
- NTP Configuration for Switch Nodes Matches Oracle VM Servers
- Hostname Matches the DNS on Oracle VM Server
- Hostname Matching with DNS on Switches
- NTP Configuration for ZFS Matches Oracle VM Servers
- NTP Configuration for ZFS Matches Physical Compute Nodes
Multiple Components
- MTU for InfiniBand Link in Control vServers

Exachk is available via MOS Doc Id. 1449226.1

Friday Jan 18, 2013

Two New Exalogic ZFS Storage Appliance MOS Notes

This week I have closed 2 Service Requests related to the ZFS Storage Appliance and I created My Oracle Support (MOS) notes from both of them as, despite they were not complicated issues and the SRs were both closed in less than one week, these procedures were still not formally documented on MOS. Below can be seen the information about these created documents.


MOS Doc Id. 1519858.1 - Will The Restart Of The NIS Service On The ZFS Storage Appliance Affect The Mounted Filesystems?

On this case, for a particular reason it was necessary to restart the NIS service. So, if for any reason, the NIS service needs to be restarted on the ZFS Storage Appliance, will the mounted filesystems be affected during the restart?

The default cluster configuration type of the ZFS storage appliance is active-passive and the storage nodes are supposed to be mirrored, so the restart of NIS should not be causing any issues; it can be done.

Note that restart of NIS should be done on the active storage head. Restarting the NIS itself will not cause any ZFS failover from Active to Passive.

In general terms, even in the event of a storage node failure, the appliance will automatically fail over to the other storage node. Under that condition, an initial degradation in performance can be expected because all of the cached data on the failed node is gone, but this effect decreases as the new active storage node begins caching data in its own SSDs.


MOS Doc Id. 1520223.1 - Exalogic Storage Nodes Hostnames Are Displayed Incorrectly

This was not the first time I saw something like this, so decided to create a note because clearly is a problem that may affect to more than one Exalogic user.

The Exalogic storage node hostnames displayed on the BUI were different than the ones displayed when accessing the node through SSH or ILOM.

This happens because for any reason the hostname is misconfigured on the ZFS Storage Appliance.

To solve this problem, it is necessary to set the system name and location accordingly on the Storage Appliance nodes BUI:
1. Login on the ZFS Storage Appliance BUI
2. Go to the "Configuration" tab, and select the "Services" subtab
3. Under the "Systems Settings" section, click on "System Identity"
4. Set the system name and location accordingly

Monday Jan 07, 2013

Exalogs - Exalogic Diagnostic Collection Tool now available on My Oracle Support

What is Exalogs?
Exalogs is a command-line tool for gathering logs, diagnostics, environment/configuration information, and other data from the following components in an Exalogic virtual rack:
- Enterprise Manager Ops Center Enterprise Controller
- Enterprise Manager Ops Center Proxy Controllers
- Oracle VM Manager
- Database VM (RDBMS)
- Compute nodes (Domain0/Dom0's)
- ZFS storage appliance
- InfniBand switches

You can target Exalogs at either the entire rack or for individual components.

Note that Exalogs is not a health-check or monitoring/reporting tool, and it is not a replacement for Exachk health-check tool.

Exalogs is available for download immediately from My Oracle Support using MOS Note 1512323.1 and further information (including a very complete README file) can be seen on that note.

Monday Jun 11, 2012

Exalogic Exachk - Exalogic Health Check Tool now available on My Oracle Support

This is a new tool for Exalogic which automates the process of determining whether an Exalogic system is in a healthy state.

Exachk is available via MOS Doc Id. 1449226.1

Check the Quick Start Guide (available in the MOS Doc. Id. mentioned above) for further informarion.

Information about the Exachk healtcheck tool for Exadata can be seen at MOS Doc Id. 1070954.1
About


Principal Technical Support Engineer in the Exalogic Enterprise Support Team (EEST).

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