Default cache file-usage purge bands as percentages of disk#3518
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jhiemstrawisc merged 2 commits intoJun 18, 2026
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jhiemstrawisc
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Closes #3519 |
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@turetske and @h2zh this is one of those loose ends I'm trying to close. I'm pinging you for review in case you have some time and interest to look at this before I merge it later this week. I've already tested manually that this is sufficient to set |
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Enabling Lotman is gated on also hand-sizing pfc.diskusage's file-usage band (Cache.FilesBaseSize/NominalSize/MaxSize), which xrootd requires to sit below the low watermark. No single absolute-size default can satisfy that on caches of differing disk sizes, so let these accept integer percentages (as the watermarks already do) and default them to percentages of total disk. Percentages scale with any cache and stay ordered below a percentage low watermark, which is the missing prerequisite for turning Lotman on without extra configuration. Scope the defaults to when Lotman is enabled, and only when the operator set none of the three, so a plain cache's purge behaviour is unchanged and the existing all-or-none rule is preserved. Because the file sizes and the low watermark can now both be percentages, validate the max-below-low-watermark ordering up front when the two are expressed the same way and defer the mixed percentage/absolute case to xrootd, which alone knows the real disk total. Also correct the documented low/high watermark defaults, which had drifted from the shipped 85/89 values. rebase
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I read through the code and they all look good. Just a small tiny trivial comment.
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Enabling Lotman is gated on also hand-sizing pfc.diskusage's file-usage band (Cache.FilesBaseSize/NominalSize/MaxSize), which xrootd requires to sit below the low watermark. No single absolute-size default can satisfy that on caches of differing disk sizes, so let these accept integer percentages (as the watermarks already do) and default them to percentages of total disk. Percentages scale with any cache and stay ordered below a percentage low watermark, which is the missing prerequisite for turning Lotman on without extra configuration.
Scope the defaults to when Lotman is enabled, and only when the operator set none of the three, so a plain cache's purge behaviour is unchanged and the existing all-or-none rule is preserved. Because the file sizes and the low watermark can now both be percentages, validate the max-below-low-watermark ordering up front when the two are expressed the same way and defer the mixed percentage/absolute case to xrootd, which alone knows the real disk total.
Also correct the documented low/high watermark defaults, which had drifted from the shipped 85/89 values.