[feature] allow for an odd number of erasure packs (#9221)

Too many deployments come up with an odd number
of hosts or drives, to facilitate even distribution
among those setups allow for odd and prime numbers
based packs.

cmd/utils.go

@@ -93,6 +93,22 @@ func path2BucketObject(s string) (bucket, prefix string) {
 	return path2BucketObjectWithBasePath("", s)
 }
 
+func getDefaultParityBlocks(drive int) int {
+	return drive / 2
+}
+
+func getDefaultDataBlocks(drive int) int {
+	return drive - getDefaultParityBlocks(drive)
+}
+
+func getReadQuorum(drive int) int {
+	return getDefaultDataBlocks(drive)
+}
+
+func getWriteQuorum(drive int) int {
+	return getDefaultDataBlocks(drive) + 1
+}
+
 // URI scheme constants.
 const (
 	httpScheme  = "http"