Author: adrian.chadd
Date: Sun May 17 07:57:42 2009
New Revision: 14049
Added:
wiki/PageName.wiki
Log:
Created wiki page through web user interface.
Added: wiki/PageName.wiki
==============================================================================
--- (empty file)
+++ wiki/PageName.wiki Sun May 17 07:57:42 2009
@@ -0,0 +1,17 @@
+#summary Store IO Load Handling
+
+= Introduction =
+
+Lusca inherited some logic for handling overloaded cache directories. This
attempts to document the basic workings, the limitations/shortcomings and
potential workarounds.
+
+= Overload during storeOpen =
+
+The store containing an object is checked via a call to the
storedir "checkload()" function. If the storedir returns error or a load
higher than 1000 it increments "store_io_stats.open.loadav_fail" and
returns NULL.
+
+If the store layer returns NULL then the store client code returns an
error via a store client callback. I have a feeling that this somehow turns
into an object "delete" from cache - either explicitly somehow due to the
error condition or a subsequent object fetch replaces the on-disk version.
This should be further investigated.
+
+= Overload during storeCreate =
+
+= Overload during read / write IO =
+
+= Problems with the load handling =
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