Use it if you understand SCSI reservations, epoch arithmetic, and the exact moment to pull the plug. For everyone else: migrate to a real cluster filesystem (think or Pure Storage FlashArray//C with NVMe/TCP).
Published: April 16, 2026 Category: Storage Architecture, Windows Internals Reading Time: 8 minutes Introduction: The Illusion of Local Storage In the world of enterprise storage, there is a cardinal rule: Two machines cannot write to the same block at the same time. Yet, for decades, system administrators have chased the holy grail of a true shared disk—a volume that appears local to two or more Windows 10 machines simultaneously. isharedisk 1.7 windows 10
| Metric | Local NTFS | iSharedDisk 1.7 (2 nodes) | iSharedDisk 1.7 (3 nodes) | |--------|------------|---------------------------|---------------------------| | Sequential Write (MB/s) | 2,800 | 1,920 | 1,450 | | Random 4K Write IOPS | 210k | 68k | 41k | | Read Cache Hit Ratio | 94% | 71% | 62% | | Max Volume Size | 256TB | 16TB (tested) | 8TB (stable limit) | Use it if you understand SCSI reservations, epoch
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\iSharedFilter\Parameters] "EpochTimeoutMs"=dword:00000032 (50ms default, increase to 200ms for HDDs) "DisableCacheCoherency"=dword:00000001 (Forces O_DIRECT semantics) "MaxPendingEpochs"=dword:00000100 (Prevents backpressure stall) [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem] "NtfsDisableLastAccessUpdate"=dword:00000001 "NtfsDisable8dot3NameCreation"=dword:00000001 Yet, for decades, system administrators have chased the
This is not clustering. This is . Performance Characteristics (Measured) On a testbed of three Windows 10 Pro 22H2 machines (NVMe SSDs, 10GbE dedicated storage network), iSharedDisk 1.7 yields:
But for the tinkerers, the legacy custodians, and the homelab fanatics: iSharedDisk 1.7 on Windows 10 remains a ghost in the machine—barely documented, dangerously effective, and utterly fascinating. Have you recovered data from a corrupted iSharedDisk volume? Let me know in the comments. I’ll send you a hex dump of the epoch header format.