{"record":{"id":"9e89b779105a4bd8","repo":"microsoft/garnet","slug":"nameof-rcs-memorysize-must-be-between-1l-lo","errorCode":null,"errorMessage":"{nameof(rcs.MemorySize)} must be between {1L << LogSettings.kMinMemorySizeBits} and {1L << LogSettings.kMaxMemorySizeBits}","messagePattern":"(.+?) must be between (.+?) and (.+?)","errorType":"exception","errorClass":"TsavoriteException","httpStatus":null,"severity":"error","filePath":"libs/storage/Tsavorite/cs/src/core/Allocator/AllocatorBase.cs","lineNumber":573,"sourceCode":"            if (logSettings.SegmentSizeBits < LogSettings.kMinMainLogSegmentSizeBits || logSettings.SegmentSizeBits > LogSettings.kMaxSegmentSizeBits)\n                throw new TsavoriteException($\"{nameof(logSettings.SegmentSizeBits)} must be between {LogSettings.kMinMainLogSegmentSizeBits} and {LogSettings.kMaxSegmentSizeBits}\");\n            if (logSettings.MemorySize != 0 && (logSettings.MemorySize < 1L << LogSettings.kMinMemorySizeBits || logSettings.MemorySize > 1L << LogSettings.kMaxMemorySizeBits))\n                throw new TsavoriteException($\"{nameof(logSettings.MemorySize)} must be between {1L << LogSettings.kMinMemorySizeBits} and {1L << LogSettings.kMaxMemorySizeBits}, or may be 0 for ReadOnly TsavoriteLog\");\n            if ((logSettings.MemorySize != 0) && (logSettings.MemorySize < (1L << logSettings.PageSizeBits) * LogSettings.kMinPageCount))\n                throw new TsavoriteException($\"{nameof(logSettings.MemorySize)} must be at least {LogSettings.kMinPageCount}x the page size ({1L << logSettings.PageSizeBits})\");\n            if (logSettings.MutableFraction < 0.0 || logSettings.MutableFraction > 1.0)\n                throw new TsavoriteException($\"{nameof(logSettings.MutableFraction)} must be >= 0.0 and <= 1.0\");\n            if (logSettings.ReadCacheSettings is not null)\n            {\n                var rcs = logSettings.ReadCacheSettings;\n                if (rcs.PageCount == 0 && rcs.MemorySize == 0)\n                    throw new TsavoriteException($\"{nameof(rcs.PageCount)} or {nameof(rcs.MemorySize)} must be specified\");\n                if (rcs.PageSizeBits < LogSettings.kMinPageSizeBits || rcs.PageSizeBits > LogSettings.kMaxPageSizeBits)\n                    throw new TsavoriteException($\"{nameof(rcs.PageSizeBits)} must be between {LogSettings.kMinPageSizeBits} and {LogSettings.kMaxPageSizeBits}\");\n                if (rcs.PageCount > MemoryUtils.ArrayMaxLength)\n                    throw new TsavoriteException($\"{nameof(rcs.PageCount)} must be less than or equal to the maximum array length ({MemoryUtils.ArrayMaxLength})\");\n                if (rcs.MemorySize != 0 && (rcs.MemorySize < 1L << LogSettings.kMinMemorySizeBits || rcs.MemorySize > 1L << LogSettings.kMaxMemorySizeBits))\n                    throw new TsavoriteException($\"{nameof(rcs.MemorySize)} must be between {1L << LogSettings.kMinMemorySizeBits} and {1L << LogSettings.kMaxMemorySizeBits}\");\n                if ((rcs.MemorySize != 0) && (rcs.MemorySize < (1L << rcs.PageSizeBits) * 2))\n                    throw new TsavoriteException($\"{nameof(logSettings.MemorySize)} must be at least twice the page size ({1L << rcs.PageSizeBits})\");\n                if (rcs.SecondChanceFraction < 0.0 || rcs.SecondChanceFraction > 1.0)\n                    throw new TsavoriteException($\"{rcs.SecondChanceFraction} must be >= 0.0 and <= 1.0\");\n            }\n\n            if (logSettings.MaxInlineKeySize < LogSettings.MinMaxInlineSize || logSettings.MaxInlineKeySize > LogSettings.MaxInlineKeySizeLimit)\n                throw new TsavoriteException($\"{nameof(logSettings.MaxInlineKeySize)} must be between {LogSettings.MinMaxInlineSize} and {LogSettings.MaxInlineKeySizeLimit}\");\n            if (logSettings.MaxInlineValueSize < LogSettings.MinMaxInlineSize || logSettings.MaxInlineValueSize > LogSettings.MaxInlineValueSizeLimit)\n                throw new TsavoriteException($\"{nameof(logSettings.MaxInlineValueSize)} must be between {LogSettings.MinMaxInlineSize} and {LogSettings.MaxInlineValueSizeLimit}\");\n\n            this.logger = logger;\n            if (logSettings.LogDevice == null)\n                throw new TsavoriteException(\"LogSettings.LogDevice needs to be specified (e.g., use Devices.CreateLogDevice, AzureStorageDevice, or NullDevice)\");\n\n            EvictCallback = evictCallback;\n\n            FlushCallback = flushCallback;","sourceCodeStart":555,"sourceCodeEnd":591,"githubUrl":"https://github.com/microsoft/garnet/blob/951b0fc6838721f89d102c2bbe1b914e8d39d700/libs/storage/Tsavorite/cs/src/core/Allocator/AllocatorBase.cs#L555-L591","documentation":"Constructor validation for the read cache: when rcs.MemorySize is non-zero it must lie in [1<<kMinMemorySizeBits, 1<<kMaxMemorySizeBits] = [1<<13, 1<<62] = [8KiB, 4EiB]. (Unlike the main-log message in error 226, this message omits the 'may be 0' note, yet the check `rcs.MemorySize != 0 && ...` does permit 0.)","triggerScenarios":"Setting ReadCacheSettings.MemorySize to a small positive value below 8KiB (e.g. 4096) when enabling the read cache.","commonSituations":"Tiny read-cache config in tests; bytes/KiB confusion; copying a snippet with a too-small value.","solutions":["Set rcs.MemorySize to 0 (meaning 'size by PageCount instead') or to a value >= 8KiB (typical: 64MiB+).","Confirm the number is in bytes."],"exampleFix":"// before\nrcs.MemorySize = 4096;        // below 8KiB floor\n// after\nrcs.MemorySize = 1L << 26;    // 64MiB","handlingStrategy":"validation","validationCode":"const long MinMem = 1L << 13, MaxMem = 1L << 62;\nif (logSettings.ReadCacheSettings is { } rcs && rcs.MemorySize != 0 && (rcs.MemorySize < MinMem || rcs.MemorySize > MaxMem))\n    throw new ArgumentOutOfRangeException(nameof(rcs.MemorySize),\n        $\"ReadCache MemorySize must be 0 or in [{MinMem},{MaxMem}]\");","typeGuard":null,"tryCatchPattern":"try { new TsavoriteKV<K,V>(logSettings, ...); }\ncatch (TsavoriteException ex) when (ex.Message.Contains(\"rcs.MemorySize\") && ex.Message.Contains(\"between\"))\n{ /* set rcs.MemorySize to 0 or >= 8KiB and recreate */ }","preventionTips":["Size the read cache with a comfortable MemorySize (e.g. 64MiB) in bytes.","Allow 0 only when sizing the read cache by PageCount."],"tags":["storage","configuration","log-settings","read-cache","memory"],"backgroundTag":null,"analyzedSha":"951b0fc6838721f89d102c2bbe1b914e8d39d700","analyzedAt":"2026-08-13T19:01:32.939Z","schemaVersion":2},"datasetVersion":"2026-08-13T19:17:28.613Z"}