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New tape server software Status and plans. CASTOR face-to-face workshop 9-10 December 2013 Eric Cano on behalf of CERN IT-DSS group. What’s being done?. Finish of the push to replace legacy tape software Started with creation of tape gateway and bridge Consolidation into a single daemon - PowerPoint PPT Presentation
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Data & Storage Services
CERN IT Department
CH-1211 Genève 23
Switzerlandwww.cern.ch/
it
DSS
New tape server softwareStatus and plans
CASTOR face-to-face workshop
9-10 December 2013
Eric Cano
on behalf of CERN IT-DSS group
CERN IT Department
CH-1211 Genève 23
Switzerlandwww.cern.ch/
it
InternetServices
DSS
2New tape server software Castor Workshop Dec 2013
What’s being done?
• Finish of the push to replace legacy tape software– Started with creation of tape gateway and bridge
• Consolidation into a single daemon– Merge stack of bridge, rtcpd, taped (and children processes)– Drop abandoned features:
• Leftovers interfaces from Shift/Castor1• Fortran format translation• Multi-tape files• User file concatenation
• Full C++, maintainable software• Interfaces will remain the same (w/exception)
– Drop-in replacement, interfacing to gateway, VDQM, VMGR, and SCSI– Logs will use the same interfaces as the stager daemon
• Will keep one process per tape mount by forking– Option to kill a session for operators
• There will be only one daemon instead of the current stack• This will imply changes on the management & monitoring
CERN IT Department
CH-1211 Genève 23
Switzerlandwww.cern.ch/
it
InternetServices
DSS
3New tape server software Castor Workshop Dec 2013
What is achieved?
• Tape SCSI (st driver + generic SCSI)– Access to tape drives has been reverse engineered– All accesses now make up the interface of “drive” objects, gathered in a single
place– All in readable C++ structures, matching the SCSI specs– Simpler device access for generic SCSI ioctl
• File structures (AUL format)– Structures have been defined, API not fully defined yet
• The threading model has been completely revisited and a proof of concept has been validated– Used to have worker thread running onto a single linked list– Now fully FIFOs based “pipelined architecture”. Each stage has its own FIFO
on input. Easy to chop the work into simple steps
• All unit tested– Still to be integrated on the master branch
• Cmake build (brought to master branch)• Documentation consolidated in a single document (tape server
handbook), and completed in parallel
CERN IT Department
CH-1211 Genève 23
Switzerlandwww.cern.ch/
it
InternetServices
DSS
4New tape server software Castor Workshop Dec 2013
What remains to be done?
• Unit testing not yet brought into Castor main branch
• SCSI and AUL support still to be merged into Castor master branch
• Threading model prototype to be made prod level (error handling, unit testing, etc…)
• Session forking has to be tested• VDQM replier to be ported from tape bridge• Link with client libraries for the rest (VMGR,
VDQM, tape gateway)• Still a lot to be done, but big subjects have been
covered
CERN IT Department
CH-1211 Genève 23
Switzerlandwww.cern.ch/
it
InternetServices
DSS
5New tape server software Castor Workshop Dec 2013
Going further (post-release 1)
• This new tape server software will allow much easier and predictable maintenance
• Some idea already floating for follow-up version:– Performance monitoring (on which FIFOs are we
waiting?)– Usage of data integrity features of the drives
CERN IT Department
CH-1211 Genève 23
Switzerlandwww.cern.ch/
it
InternetServices
DSS
6New tape server software Castor Workshop Dec 2013
Timeline
• Development started last summer• Targeting delivery for end H1 ’14• First release will be double release
– Like tape gateway
• Early testing welcome (to assess impact of changes on other sites)