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Chapter 9: Tricks, Tips and Helpful Hints
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9.1 Using HSI to Backup Filesystems
A common method
of backing up large filesystems on UNIX workstations is to Use the `tar' utility
in conjunction with HSI to create a backup file on HPSS, by piping the output
of TAR to HSI. For example, suppose you wish to backup the filesystem "/usr".
Enter the following:
cd/
(changes working directory to one level before
"usr")
tar cf - usr | HSI save -:usr.tar
To retrieve the
file segments and recreate the original directory contents, enter
HSI
get -:usr.tar | tar xf -
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- Example:
Using ? as a Wildcard Filter
The * (asterisk) is the "wildest" of the wildcards: it can stand for any
character in any string of any length. The ? (question mark) wildcard character,
however, can stand for a pattern of only one character. It can be used to
filter names not only by their content but also by their length.
The following
example shows you how to delete files with names of two characters in
the directory `~/backup' and any file that has a two-character name and
starts with 'f` in the subdirectory /original/94nov.
rm
~/backup/?? /original/94nov/f?
- Example:
Using a Wildcard filter to refer to a single node
Using wildcards can often reduce the amount of typing in a command when
only a single nodename is desired; for example, assume that the following
files exist on HPSS:
TestData-RunNumber3-10July1993
TestData-RunNumber4-10July1993
TestData-RunNumber5-10July1993
Any of the
following commands can be used to refer to the second of these files:
get datafile : TestData-RunNumber4-10July1993
get datafile: *4*93
get datafile : *4-*
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9.3 File Integrity and Backup
HPSS stores data on mirrored disk and put two copies on
separate tapes. However, no archive or offsite backup of data is made. It
is your responsibility to back up critical files!
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9.4 Using Recursion for Project Management
You can use the
recursion features available in HSI to simplify the management of projects.
The GET, LS, SAVE, STORE and RM commands all support recursion by specifying
`-R'. For example, suppose your project consists of the directory tree:
MyProject (root)
Source
Include
h1.h
h2.h
h3.h
CFiles
file1.c
file2.c
file3.c
Binaries
Programs
myproject
Relocatables
file1.o
file2.o
file3.o
then the command
can be used to
save the directory "MyProject" and all of its files and subdirectories, automatically
creating subdirectories as required.
Conversely,
the command
can be used to fetch the directory and all of its files
and subdirectories, automatically creating local subdirectories as required.
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9.5 Frequently Used Requests
If you have a set of HSI keywords that you often use to
establish your HPSS keyset environment, you should consider setting the values
and keeping them as a keyset. See KEEP Command and ADOPT Command in Chapter
7.
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9.6 Listing Very Large Directories
It may sometimes be necessary to list HPSS directories
containing a very large number of nodes. Normally, the entire set of directory
entry names is first read into memory and sorted to allow for listing by columns,
rows, etc. If this fails due to memory exhaustion or it simply takes too long,
the "-O" option may be specified on the LS command to cause the directory entries
to be listed in the order that they are read, and not attempt to sort them.
This is also the fastest method of listing a directory.
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9.7 Retrieving Large Files
Users having trouble retrieving files over 25 GB in size
may wish to use the -S option
for the get or mget
commands. The -S option
was added to allow users to disable staging files from tape, specifically
for this type of situation. The syntax is:
get -S [other options] local : hpss [local : hpss ...]
The usage message that is displayed by typing "get"
with no options, will also explain the -S
flag.
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9.8 Operating System Considerations
for One-Liners
Special considerations
apply to HSI one-liner requests which contain certain characters, including
wild card characters. Some operating systems and some command languages have
defined certain characters, such as the asterisk (*) and the double quote("),
to have special meanings, so procedures should be followed if such characters
are to be passed to HSI without local interpretation. UNIX-based systems support
wildcards, but in varying ways, depending upon the command shell in use, so
you should know the effect these systems will have on your results.
- If wildcard
pattern-matching is to be done by HSI only, the wildcard path in a one-liner
should always be enclosed in single or double quotes or the wildcard characters
should be preceded by the escape character (\). When wild path is "quoted"
or "escaped" in this way, local wildcard processing will not be invoked
for the quoted string; the string will be passed without substitution
to HSI.
- Conversely,
an "unprotected" path will be processed by the shell and the wildcard
pattern will be resolved in terms of local files, and then passed on to
HPSS. For example, to preserve a wildpath so that only HSI will process
it enter
- These techniques
do not apply if HSI is used in interactive mode instead of single-line
mode. They also do not apply to HSI commands read from IN files.
Be aware when
using locally supported wildcard capabilities that HPSS restrictions on legal
file name characters and legal file name length will still apply. You should
be wary when using wildcards in HSI paths in command files.
See Operating
System Considerations for UNIX-Based Systems in Section 4 for more operating
system-specific information.
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