I googled GPFS_FCNTL_GET_DATABLKDISKIDX and found this discussion:
https://www.ibm.com/developerworks/community/forums/html/topic?id=db48b190-4f2f-4e24-a035-25d3e2b06b2d&ps=50 In general, GPFS files ARE deliberately "fragmented" but we don't say that - we say they are "striped" over many disks -- and that is generally a good thing for parallel performance. Also, in GPFS, if the last would-be block of a file is less than a block, then it is stored in a "fragment" of a block. So you see we use "fragment" to mean something different than other file systems you may know. --marc From: Aaron Knister <[email protected]> To: gpfsug main discussion list <[email protected]> Date: 11/04/2017 12:22 PM Subject: [gpfsug-discuss] file layout API + file fragmentation Sent by: [email protected] I've got a question about the file layout API and how it reacts in the case of fragmented files. I'm using the GPFS_FCNTL_GET_DATABLKDISKIDX structure and have some code based on tsGetDataBlk.C. I'm basing the block size based off of what's returned by filemapOut.blockSize but that only seems to return a value > 0 when filemapIn.startOffset is 0. In a case where a file were to be made up of a significant number of non-contiguous fragments (which... would be awful in of itself) how would this be reported by the file layout API? Does the interface technically just report the disk location information of the first block of the $blockSize range and assume that it's contiguous? Thanks! -Aaron -- Aaron Knister NASA Center for Climate Simulation (Code 606.2) Goddard Space Flight Center (301) 286-2776 _______________________________________________ gpfsug-discuss mailing list gpfsug-discuss at spectrumscale.org https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwICAg&c=jf_iaSHvJObTbx-siA1ZOg&r=cvpnBBH0j41aQy0RPiG2xRL_M8mTc1izuQD3_PmtjZ8&m=wnR7m6d4urZ_8dM4mkHQjMbFD9xJEeesmJyzt1osCnM&s=-dgGO6O5i1EqWj-8MmzjxJ1Iz2I5gT1aRmtyP44Cvdg&e=
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