diff --git src/fs/rock/RockSwapDir.cc src/fs/rock/RockSwapDir.cc
index 4aefc21..9673712 100644
--- src/fs/rock/RockSwapDir.cc
+++ src/fs/rock/RockSwapDir.cc
@@ -427,7 +427,8 @@ Rock::SwapDir::canStore(const StoreEntry &e, int64_t diskSpaceNeeded, int &load)
 
     // Do not start I/O transaction if there are less than 10% free pages left.
     // TODO: reserve page instead
-    if (Ipc::Mem::PageLevel(Ipc::Mem::PageId::ioPage) >= 0.9 * Ipc::Mem::PageLimit(Ipc::Mem::PageId::ioPage)) {
+    if (needsDiskStrand() &&
+        Ipc::Mem::PageLevel(Ipc::Mem::PageId::ioPage) >= 0.9 * Ipc::Mem::PageLimit(Ipc::Mem::PageId::ioPage)) {
         debugs(47, 5, HERE << "too few shared pages for IPC I/O left");
         return false;
     }
@@ -520,7 +521,8 @@ Rock::SwapDir::openStoreIO(StoreEntry &e, StoreIOState::STFNCB *cbFile, StoreIOS
 
     // Do not start I/O transaction if there are less than 10% free pages left.
     // TODO: reserve page instead
-    if (Ipc::Mem::PageLevel(Ipc::Mem::PageId::ioPage) >= 0.9 * Ipc::Mem::PageLimit(Ipc::Mem::PageId::ioPage)) {
+    if (needsDiskStrand() &&
+        Ipc::Mem::PageLevel(Ipc::Mem::PageId::ioPage) >= 0.9 * Ipc::Mem::PageLimit(Ipc::Mem::PageId::ioPage)) {
         debugs(47, 5, HERE << "too few shared pages for IPC I/O left");
         return NULL;
     }