microsoft/garnet · error · TsavoriteException

{nameof(rcs.MemorySize)} must be between {1L << LogSettings.

Error message

{nameof(rcs.MemorySize)} must be between {1L << LogSettings.kMinMemorySizeBits} and {1L << LogSettings.kMaxMemorySizeBits}

What it means

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.)

Source

Thrown at libs/storage/Tsavorite/cs/src/core/Allocator/AllocatorBase.cs:573

            if (logSettings.SegmentSizeBits < LogSettings.kMinMainLogSegmentSizeBits || logSettings.SegmentSizeBits > LogSettings.kMaxSegmentSizeBits)
                throw new TsavoriteException($"{nameof(logSettings.SegmentSizeBits)} must be between {LogSettings.kMinMainLogSegmentSizeBits} and {LogSettings.kMaxSegmentSizeBits}");
            if (logSettings.MemorySize != 0 && (logSettings.MemorySize < 1L << LogSettings.kMinMemorySizeBits || logSettings.MemorySize > 1L << LogSettings.kMaxMemorySizeBits))
                throw new TsavoriteException($"{nameof(logSettings.MemorySize)} must be between {1L << LogSettings.kMinMemorySizeBits} and {1L << LogSettings.kMaxMemorySizeBits}, or may be 0 for ReadOnly TsavoriteLog");
            if ((logSettings.MemorySize != 0) && (logSettings.MemorySize < (1L << logSettings.PageSizeBits) * LogSettings.kMinPageCount))
                throw new TsavoriteException($"{nameof(logSettings.MemorySize)} must be at least {LogSettings.kMinPageCount}x the page size ({1L << logSettings.PageSizeBits})");
            if (logSettings.MutableFraction < 0.0 || logSettings.MutableFraction > 1.0)
                throw new TsavoriteException($"{nameof(logSettings.MutableFraction)} must be >= 0.0 and <= 1.0");
            if (logSettings.ReadCacheSettings is not null)
            {
                var rcs = logSettings.ReadCacheSettings;
                if (rcs.PageCount == 0 && rcs.MemorySize == 0)
                    throw new TsavoriteException($"{nameof(rcs.PageCount)} or {nameof(rcs.MemorySize)} must be specified");
                if (rcs.PageSizeBits < LogSettings.kMinPageSizeBits || rcs.PageSizeBits > LogSettings.kMaxPageSizeBits)
                    throw new TsavoriteException($"{nameof(rcs.PageSizeBits)} must be between {LogSettings.kMinPageSizeBits} and {LogSettings.kMaxPageSizeBits}");
                if (rcs.PageCount > MemoryUtils.ArrayMaxLength)
                    throw new TsavoriteException($"{nameof(rcs.PageCount)} must be less than or equal to the maximum array length ({MemoryUtils.ArrayMaxLength})");
                if (rcs.MemorySize != 0 && (rcs.MemorySize < 1L << LogSettings.kMinMemorySizeBits || rcs.MemorySize > 1L << LogSettings.kMaxMemorySizeBits))
                    throw new TsavoriteException($"{nameof(rcs.MemorySize)} must be between {1L << LogSettings.kMinMemorySizeBits} and {1L << LogSettings.kMaxMemorySizeBits}");
                if ((rcs.MemorySize != 0) && (rcs.MemorySize < (1L << rcs.PageSizeBits) * 2))
                    throw new TsavoriteException($"{nameof(logSettings.MemorySize)} must be at least twice the page size ({1L << rcs.PageSizeBits})");
                if (rcs.SecondChanceFraction < 0.0 || rcs.SecondChanceFraction > 1.0)
                    throw new TsavoriteException($"{rcs.SecondChanceFraction} must be >= 0.0 and <= 1.0");
            }

            if (logSettings.MaxInlineKeySize < LogSettings.MinMaxInlineSize || logSettings.MaxInlineKeySize > LogSettings.MaxInlineKeySizeLimit)
                throw new TsavoriteException($"{nameof(logSettings.MaxInlineKeySize)} must be between {LogSettings.MinMaxInlineSize} and {LogSettings.MaxInlineKeySizeLimit}");
            if (logSettings.MaxInlineValueSize < LogSettings.MinMaxInlineSize || logSettings.MaxInlineValueSize > LogSettings.MaxInlineValueSizeLimit)
                throw new TsavoriteException($"{nameof(logSettings.MaxInlineValueSize)} must be between {LogSettings.MinMaxInlineSize} and {LogSettings.MaxInlineValueSizeLimit}");

            this.logger = logger;
            if (logSettings.LogDevice == null)
                throw new TsavoriteException("LogSettings.LogDevice needs to be specified (e.g., use Devices.CreateLogDevice, AzureStorageDevice, or NullDevice)");

            EvictCallback = evictCallback;

            FlushCallback = flushCallback;

View on GitHub (pinned to 951b0fc683)

Solutions

  1. Set rcs.MemorySize to 0 (meaning 'size by PageCount instead') or to a value >= 8KiB (typical: 64MiB+).
  2. Confirm the number is in bytes.

Example fix

// before
rcs.MemorySize = 4096;        // below 8KiB floor
// after
rcs.MemorySize = 1L << 26;    // 64MiB
Defensive patterns

Strategy: validation

Validate before calling

const long MinMem = 1L << 13, MaxMem = 1L << 62;
if (logSettings.ReadCacheSettings is { } rcs && rcs.MemorySize != 0 && (rcs.MemorySize < MinMem || rcs.MemorySize > MaxMem))
    throw new ArgumentOutOfRangeException(nameof(rcs.MemorySize),
        $"ReadCache MemorySize must be 0 or in [{MinMem},{MaxMem}]");

Try / catch

try { new TsavoriteKV<K,V>(logSettings, ...); }
catch (TsavoriteException ex) when (ex.Message.Contains("rcs.MemorySize") && ex.Message.Contains("between"))
{ /* set rcs.MemorySize to 0 or >= 8KiB and recreate */ }

Prevention

When it happens

Trigger: Setting ReadCacheSettings.MemorySize to a small positive value below 8KiB (e.g. 4096) when enabling the read cache.

Common situations: Tiny read-cache config in tests; bytes/KiB confusion; copying a snippet with a too-small value.

Related errors

AI-assisted analysis of microsoft/garnet@951b0fc683 (2026-08-13). Data as JSON: /api/errors/9e89b779105a4bd8. Report an issue: GitHub.