Status of the Channel Access
Zippy Archiver (CZAR)
B. Bevins, et. al.
April 28, 2005
EPICS Collaboration
Controls Group
Outline
 Status
 Performance
 Limitations
 Development Activities
 New
Features
 Future Plans
April 28, 2005
EPICS Collaboration
Controls Group
Status

CZAR has been our production archiver for
over a year.
 Common History API (HAPI) supplies data to:



XARR, StripTool, ArchiveViewer
hapiget (command line tool)
TCL programs using the Combat ORB
• A working prototype of a TCL archive viewer was
written in an afternoon!

Specialized data collection such as eventtriggered mode has reduced the need for
other data collection tools.
 Lead developer left for private industry
April 28, 2005
EPICS Collaboration
Controls Group
TCL Archive Viewer
April 28, 2005
EPICS Collaboration
Controls Group
Performance Data
 37,272
signals connected
 Stores about 2 GB/day
 About 810 GB of data available online
dating back to June 2004
 253.5 billion data points available
online
 Platform:

Redhat ES3, dual 3GHz P4, 16 GB
memory, 1 TB RAID array
April 28, 2005
EPICS Collaboration
Controls Group
Retrieval Performance
1000
10000
100
1000
10
100
1
10
0.1
Samples/Sec
Sec
Worst Time
Best Time
Best Samples/Sec
1
1
10
100
1000
10000 10000 1E+06 1E+07
# Samples Fetched 0
April 28, 2005
EPICS Collaboration
Controls Group
Limitations

Data acquisition engine has failed a few
times


Scaling issues
Data retrieval server fails often, requiring
constant monitoring

Possibly vulnerable to ill-behaved clients

Initial version is incompletely documented
 Backup system only partially implemented
and not automated
April 28, 2005
EPICS Collaboration
Controls Group
Limitations

Awkward management of data streams and
groups


results in archiving unneeded streams
Scaling problem with original design



many data “chunks” contain only one point in
time, resulting in very large database tables
causes slow data retrieval times
one system failure was a table index overflow!
April 28, 2005
EPICS Collaboration
Controls Group
Development Activities

Goal is to achieve a stable system requiring
minimal monitoring
 New version is test case project using more
rigorous Software Engineering practices

Formal requirements, design review,
development standards, code review,
testing…
April 28, 2005
EPICS Collaboration
Controls Group
New Features

Automated backups to Computer Center tape
silos (we’re a drop in the bucket to them)
 Stream/group management policies and tools
to assist in management
 Data culling capabilities similar to Epics ADEL
but will work on fields other than .VAL
 Fixing and documenting the data retrieval
access mechanism
April 28, 2005
EPICS Collaboration
Controls Group
Future Plans

Decommissioning system clogged with
redundant and damaged data
 Starting over with a clean database using
data culling wherever appropriate
 Managing stream requests so data is only
archived for the period of user interest
 High performance lossless data compression
April 28, 2005
EPICS Collaboration
Controls Group
Summary

Current czar archiver is meeting customer
needs, but has problems
 Development activities are underway to shore
up holes in the current system
 Planning to start with a fresh system that is
more thoroughly engineered and tested up
front
April 28, 2005
EPICS Collaboration
Controls Group
Status of the Channel Access
Zippy Archiver (CZAR)
B. Bevins, et. al.
April 28, 2005
EPICS Collaboration
Controls Group