reduce the default volume size to 32000MB from 32768MB

this avoids problems with busy writing systems from having too many file
id assigned while the volume is close to the overflow limit.

go/weed/server.go

@@ -44,7 +44,7 @@ var (
 	serverPeers               = cmdServer.Flag.String("peers", "", "comma separated ip:masterPort list")
 	masterPort                = cmdServer.Flag.Int("masterPort", 9333, "master server http listen port")
 	masterMetaFolder          = cmdServer.Flag.String("mdir", os.TempDir(), "data directory to store meta data")
-	masterVolumeSizeLimitMB   = cmdServer.Flag.Uint("volumeSizeLimitMB", 32*1024, "Default Volume Size in MegaBytes")
+	masterVolumeSizeLimitMB   = cmdServer.Flag.Uint("volumeSizeLimitMB", 32*1000, "Default Volume Size in MegaBytes")
 	masterConfFile            = cmdServer.Flag.String("conf", "/etc/weedfs/weedfs.conf", "xml configuration file")
 	masterDefaultRepType      = cmdServer.Flag.String("defaultReplicationType", "000", "Default replication type if not specified.")
 	volumePort                = cmdServer.Flag.Int("port", 8080, "volume server http listen port")