Databases Reference
In-Depth Information
If
tnsping
works, it means that the remote listener is up and working. It doesn't necessarily mean that the
database is up, so you may need to log in to the database server to investigate further. If
tnsping
doesn't work, then
the listener or the database is down or hung.
To further investigate issues, I log in directly to the server to perform additional checks, such as a mount point's
filling up.
OraCLe INStaNt CLIeNt
i work with sAs and developers who sometimes need to test remote connectivity to a database but who don't
have access to an oracle installation with the sQl*plus executable. in these situations, i recommend that they
download and use oracle instant Client. it has a very small footprint and takes just a few minutes to install. here
are the steps:
1.
Download the instant Client from the technology network area of the oracle web site
2.
Create a directory for storing the files.
3.
unzip the files to that directory.
4.
set the
LD_LIBRARY_PATH
and
PATH
variables to include the directory to which the files were
unzipped.
5.
Connect to a remote database, using the easy connect syntax:
$ sqlplus user/pass@'host:port/database_service_name'
this process allows you to access sQl*plus without having to perform a large and cumbersome oracle install.
instant Client is available for most hardware platforms (Windows, Mac, linux, and unix).
Investigating Disk Fullness
To further diagnose issues (such as running low on disk space), you need to log in directly to the remote server.
Typically, you will need to log in as the owner of the Oracle software (usually the
oracle
OS account). When first
logging in to a box, one issue that will cause a database to hang or have problems is a full mount point. The
df
command with the human readable
-h
switch assists with verifying disk fullness:
$ df -h
Any mount point that is full needs to be investigated. If the mount point that contains
ORACLE_HOME
becomes full,
then you'll receive errors such as this when connecting to the database:
Linux Error: 28: No space left on device
To fix issues with a full mount point, first identify files that can be either moved or removed. Generally, I start by
looking for old trace files; often, there are old files that can be safely removed.
