Support #6163

Review Request #6135: Data Management Workflow Umbrella Task

Can't check checksum in /pnfs/scratch, breaks some storage methods

Added by Heidi Schellman about 6 years ago. Updated about 6 years ago.

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Duration: 16


dcache doesn't allow direct file reads so can't check checksums for files written to /pnfs/minerva/scratch.

This breaks the checks we make before putting files into the dropbox.

We either need to reenable this or eliminate all possible race conditions from productions.

Right now /pnfs/ gets the first version of multiple copies while the metadata on bluearc is last.

Possible solutions:

1) declare metadata on farm node - will force first copy to have correct metadata, erase output if declaration fails. Will require substantial testing

2) find a way to do checksums on /pnfs/ it's dangerous not to be able to validate transfers anyways. Switch to different checksum which does work? Have ifdh write the checksum someplace?

3) put in robust locking system to prevent multiple submissions - we have this (99.9% of the time) for keepup but failures still occur occasionally.

4) put unique timestamp in each filename - opens us up to multiple copies with the same content - will need to add a checker to prevent such duplicates.

Related issues

Related to MINERvA Software Infrastructure - Support #6118: Test Data Production into dCache ScratchClosed05/02/201406/18/2014


#1 Updated by Gabriel Perdue about 6 years ago

Do files in dCache already have checksums?

There is a command-line option:

checksum_dcache() {
mknod /tmp/fifo$$ p
samweb file-checksum /tmp/fifo$$ &
ifdh cp $1 /tmp/fifo$$ &
rm /tmp/fifo$$

From Marc Mengel, but we may want something built directly into samweb that offers a more unified interface.

#2 Updated by Gabriel Perdue about 6 years ago

  • Due date set to 05/19/2014

#3 Updated by Gabriel Perdue about 6 years ago

  • Parent task set to #6135

#4 Updated by Heidi Schellman about 6 years ago

  • Status changed from New to Closed
  • Assignee set to Marc Mengel
  • % Done changed from 0 to 100

Mark Mengel gave us a script which is in production_tools and will be in ifdh_utils in future.

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