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  • Enscribe File and Slack space

    From wilso...@gmail.com@wilsonjohna@gmail.com to comp.sys.tandem on Thu Jun 29 12:56:36 2023
    From Newsgroup: comp.sys.tandem

    Hi All -

    I am curious if anyone can shed some light on how slack space works on a key sequenced Enscribe file. I looked in the manuals and see small references, but not a great explanation.

    If slack is removed from a file using something like FUP RELOAD, that appears to reduce the file size. (Smaller files are typically a good thing.)

    However, does this also mean that the subsequent writes to that file will now need to allocate blocks of space prior to inserting a record? If so, I would assume this would decrease the disk I/O efficiency?

    Thanks for any insights!

    --- Synchronet 3.21d-Linux NewsLink 1.2
  • From Randall@rsbecker@nexbridge.com to comp.sys.tandem on Fri Jun 30 11:44:33 2023
    From Newsgroup: comp.sys.tandem

    On Thursday, June 29, 2023 at 3:56:38rC>p.m. UTC-4, wilso...@gmail.com wrote:
    Hi All -

    I am curious if anyone can shed some light on how slack space works on a key sequenced Enscribe file. I looked in the manuals and see small references, but not a great explanation.

    If slack is removed from a file using something like FUP RELOAD, that appears to reduce the file size. (Smaller files are typically a good thing.)

    However, does this also mean that the subsequent writes to that file will now need to allocate blocks of space prior to inserting a record? If so, I would assume this would decrease the disk I/O efficiency?

    Thanks for any insights!
    Slack is configured when the file is created or altered. It comes in two forms: DSLACK (record space) and ISLACK (index space). By default, FILE_WRITEX_ respects these values and leaves slack in the file for future insert efficiency at the cost of space. RELOAD removes the slack so subsequent inserts can be more expensive by causing new items to move or reorganize existing bytes to provide space for the inserts.
    --Randall
    --- Synchronet 3.21d-Linux NewsLink 1.2
  • From wilso...@gmail.com@wilsonjohna@gmail.com to comp.sys.tandem on Tue Jul 11 10:44:30 2023
    From Newsgroup: comp.sys.tandem

    Thanks! I think that confirms what I was expecting.
    On Friday, June 30, 2023 at 2:44:35rC>PM UTC-4, Randall wrote:
    On Thursday, June 29, 2023 at 3:56:38rC>p.m. UTC-4, wrote:
    Hi All -

    I am curious if anyone can shed some light on how slack space works on a key sequenced Enscribe file. I looked in the manuals and see small references, but not a great explanation.

    If slack is removed from a file using something like FUP RELOAD, that appears to reduce the file size. (Smaller files are typically a good thing.)

    However, does this also mean that the subsequent writes to that file will now need to allocate blocks of space prior to inserting a record? If so, I would assume this would decrease the disk I/O efficiency?

    Thanks for any insights!
    Slack is configured when the file is created or altered. It comes in two forms: DSLACK (record space) and ISLACK (index space). By default, FILE_WRITEX_ respects these values and leaves slack in the file for future insert efficiency at the cost of space. RELOAD removes the slack so subsequent inserts can be more expensive by causing new items to move or reorganize existing bytes to provide space for the inserts.
    --Randall
    --- Synchronet 3.21d-Linux NewsLink 1.2