Frequently Asked Questions
There is a related page of Common Installation Problems.
How to recover from a corrupted ODB
- Stop your front-ends, mlogger, mhttpd, etc.
- Remove the shared memory associated to ODB buffer. Find the shared memory segment by doing
ls -l /dev/shm
then remove the segment that will be something like /dev/shm/*_test_ODB_SHM where "test" is the experiment name.
- Move the old ODB files. These will be in the location given by Exptab, e.g. ~/online
cd online mv .ODB.SHM .ODB.SHM.BAD
- Restart ODB with larger size using odbedit e.g.
odbedit -s 100000000
- Reload the last saved ODB dump you have (see save and reload the ODB). These dumps are typically called something like 'online/history/*.xml'.
So from odbedit you do something like
odbedit> load history/run00071.xml
- Your ODB should now be fixed.
Note that sometimes it seems that you also need to remove the buffers associated with the system messages (called SYSMSG) as well as the buffers associated with the ODB.
See also odbinit.
How to get odbedit to show run state
Question: I've seen the ODB prompt displaying the run state, how do you do that?
Answer: Modify the /System/prompt field. The "S" is the trick.
Fri> odb -e bnmr1 -h isdaq01 [host:expt:Stopped]/cd /System/ [host:expt:Stopped]/System>ls Clients Client Notify 0 Prompt [%h:%e:%S]%p Tmp [host:expt:Stopped]/System [host:expt:Stopped]/Systemset prompt [%h:%e:%S]%p> [host:expt:Stopped]/System>ls Clients Client Notify 0 Prompt [%h:%e:%S]%p> Tmp [host:expt:Stopped]/System>set Prompt [%h:%e:%s]%p> [host:expt:S]/System>set Prompt [%h:%e:%S]%p> [host:expt:Stopped]/System>
See also /System ODB tree#Prompt.
MIDAS, by default, allows you to have a maximum of 256 individual hot-links to be registered. If you find that you need more hot-links than that, follow the procedure below:
- Use odbedit to save current ODB
odbedit save current_odb.odb
- Stop all the running MIDAS processes, including mlogger and mserver using the web
interface. Then stop mhttpd as well. To stop mhttpd just do
- Remove your old ODB (we will recreate it after modifying MIDAS, using the backup you just
mv .ODB.SHM .ODB.SHM.20161104 rm /dev/shm/<expname>_ODB_SHM
where <expname> is the name of your experiment.
- 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
- Rebuild MIDAS
cd $MIDASSYS make clean; make
- Create new ODB
odbedit -s 1000000
Note, you should change the size of the ODB to whatever you need.
- reload your original ODB
[local:exp:Stopped] load current_odb.odb
- Rebuild all your frontend programs (and other user-specific programs) against new MIDAS; they should then work and you should be able to produce more open records.