FAQ

Frequently Asked Questions

There is a related page of Common Installation Problems.

Increasing Number of Hot-links

1. Use odbedit to save current ODB

 odbedit
save current_odb.odb 

1. Stop all the running MIDAS processes, including mlogger and mserver using the web

interface. Then stop mhttpd as well.

1. Remove your old ODB (we will recreate it after modifying MIDAS, using the backup you just

made).

mv .ODB.SHM .ODB.SHM.20161104
rm /dev/shm/thomas_ODB_SHM

1. Make the following modifications to midas. In this particular case I have increased the

max number of open records from 256 to 1024. You would need to change the constants if you want to change to other values

diff --git a/include/midas.h b/include/midas.h
index 02b30dd..33be7be 100644
--- a/include/midas.h
+++ b/include/midas.h
@@ -254,7 +254,7 @@ typedef std::vector<std::string> STRING_LIST;
-#define MAX_OPEN_RECORDS       256           /**< number of open DB records   */
+#define MAX_OPEN_RECORDS       1024           /**< number of open DB records   */
diff --git a/src/odb.c b/src/odb.c
index 47ace8f..ac1bef3 100755
--- a/src/odb.c
+++ b/src/odb.c
@@ -699,8 +699,8 @@ static void db_validate_sizes()
-   assert(sizeof(DATABASE_CLIENT) == 2112);
-   assert(sizeof(DATABASE_HEADER) == 135232);
+   assert(sizeof(DATABASE_CLIENT) == 8256);
+   assert(sizeof(DATABASE_HEADER) == 528448);

The calculation is as follows (in case you want a different number of open records): DATABASE_CLIENT = 64 + 8*MAX_OPEN_ERCORDS = 64 + 8*1024 = 8256 DATABASE_HEADER = 64 + 64*DATABASE_CLIENT = 64 + 64*8256 = 528448

1. Rebuild MIDAS

make clean; make

1. Create new ODB

odbedit -s 1000000

Note, you should change the size of the ODB to whatever you need.

1. reload your original ODB

load  current_odb.odb

1. Rebuild your frontend against new MIDAS; then it should work and you should be able to

produce more open records.