If when your attempt to create device meta-data fails this is drbd preventing you from corrupting a file system present on the target partition.
$ drbdadm create-md drbd0
v08 Magic number not found
md_offset 30005817344
al_offset 30005784576
bm_offset 30004867072
Found ext2 filesystem which uses 190804004 kB
current configuration leaves usable 29301628 kB
Device size would be truncated, which
would corrupt data and result in
'access beyond end of device' errors.
You need to either
* use external meta data (recommended)
* shrink that filesystem first
* zero out the device (destroy the filesystem)
Operation refused.
Command 'drbdmeta /dev/drbd0 v08 /dev/sda4 internal create-md' terminated with exit code 40
drbdadm aborting
Once you have confirmed that the file system present on the target partition is no longer required at the prompt type the following:
Replace /dev/sdaX with the block device you are targeting.
dd if=/dev/zero of=/dev/sdaX bs=1M count=128
Once this has completed the drbdadm create-md drbd0 command will complete with a "success."
$ drbdadm create-md drbd0
v08 Magic number not found
v07 Magic number not found
v07 Magic number not found
v08 Magic number not found
Writing meta data...
initialising activity log
NOT initialized bitmap
New drbd meta data block successfully created.
success
$
If you want details about how storage devices are performing on Redhat/Centos/Fedora use the vmstat and iostat commands.
After installing Centos 5.3 the iostat command is not available. To install it use yum:
# yum install sysstat
Opening SSH to the outside world is a security risk. Here is how to restrict SSH access to certain IP addresses on a machine.
- Edit the /etc/hosts.allow file to include these lines, assuming your machine is on the 192.168.2.x nonrouting IP block, and you want to enable an external address of 217.40.111.121 IP block: Remember to add the period on the end of each incomplete IP number. If you have another complete IP address or range, add a space and that range on the end.
sshd,sshdfwd-X11: 192.168.2. 217.40.111.121
- Edit your /etc/hosts.deny file to include this line:
sshd,sshdfwd-X11:ALL
- These lines refuse SSH connections from anyone not in the IP address blocks listed.
Additionally you can restrict SSH access by username.
- Edit the /etc/ssh/sshd_config file and add the following lines
PermitRootLogin no
AllowUsers user1 user2 user3 etc
PasswordAuthentication yes
Now restart the ssh daemon for these changes to take effect
service sshd restart
Each Recital table can have one or more data dictionaries to provide a central repository for constraints and other metadata.
Here's how to set up field validation for a field with a small static number of acceptable values.
Using the example.dbf table from the southwind sample database, validation can be added to the title field to ensure it matches one of a list values.
If you have access to the Recital Workbench, you can use the modify structure worksurface to add and alter your dictionary entries, including a customized error message if required.
Here's how to set up field validation for a field with a small static number of acceptable values.
Using the example.dbf table from the southwind sample database, validation can be added to the title field to ensure it matches one of a list values.
open database southwindThe inlist() function checks whether the specified expression exists in the comma-separated list which follows. An attempt to update title with a value not in the list will give an error: Validation on field 'TITLE' failed.
alter table example add constraint;
(title set check inlist(alltrim(title),"Miss","Mr","Mrs","Ms"))
If you have access to the Recital Workbench, you can use the modify structure worksurface to add and alter your dictionary entries, including a customized error message if required.
Subclipse is an Eclipse Team Provider plug-in providing support for Subversion within the Eclipse IDE. This plugin is required in order to use the recital eclipse workspace.
Recital implements SQL-92 and most of the SQL-99 standard for SQL, but also provides lower level navigational data access for performing high transaction throughput. It is the choice of the application developer whether to use SQL, navigational data access, or a combination of both depending upon the type of application being developed.
Recital is a proven and cost-effective database solution that will help reduce the cost of your database and application software infrastructure substantially. As an added benefit, Recital can run many legacy applications with little to no change as it understands FoxBASE, FoxPRO and Clipper languages as a subset of it's overall capability.
Recital 10 enhances the SQL optimizer. Now, production indexes with a FOR <conditions> will be used to optimize SQL SELECT statements. If a WHERE <condition> on a SELECT statement matches a FOR <condition> on an index tag, this index will be used to optimize the query. The WHERE <condition> must be an exact match with the FOR <condition>. For example;
USE accounts INDEX on account_no TAG outstanding FOR balance > 0 EXPLAIN SELECT * FROM accounts WHERE balance > 0 Optimized using for condition on tag 'OUTSTANDING'
When using Recital on linux you can integrate your favorite linux shell commands and use then directly inside Recital using the alias command. This can be particularly useful when you ssh into a remote system and run recital. You can then issue linux commands without having to open another terminal session. Several aliased shell commands are predefined in /opt/recital/conf/config.db. You can add others to suit your needs.
On my system i have these commands aliased.
The alias command handles parameter substitition.
alias pwd "? default()"
alias cp "copy file "
alias mv "rename "
alias rm "erase "
alias ls "run('ls $0')"
alias ps "run('ps $0')"
alias grep "run('grep $0')"
alias cd "set default to $1"
alias cls "clear screen"
These commands can now be used inside the Recital command window just as you would use them at the linux prompt, including the ability to pipe commands together.
ls -l | grep .prg ps -elf | grep db.exeThe run() function that is used to run the shell command as specified in the alias command will capture output and display it in a text viewer. If you want to run the command and display the contents full screen, then specify true as the third parameter to the run().
run("command", true, true)
The arguments to run() are as follows.
| Argument | Description |
|---|---|
| 1 | the command line to run |
| 2 | True if output should be displayed in a text area (default True) |
| 3 | True if the output should be displayed full screen (default False) |
| Macro | Description |
|---|---|
| $0 | the command line following the command name |
| $1..$n | the arguments given to the command |
We are pleased to announce the release of Recital 10.0.3.
Here is a brief list of features and functionality that you will find in the 10.0.3 release.
- New Commands:
- SET TMPNAMPATH ON|OFF
- REMOVE TABLE - New Functions:
- CURSORGETPROP()
- CURSORSETPROP()
- CURVAL()
- GETFLDSTATE()
- OLDVAL()
- TABLEREVERT()
- TABLEUPDATE()
- SETFLDSTATE() - Enhanced Functions:
- TMPNAM() - additional parameter to specify the return of basename only
- MAILATTACH() - parameter changed from array to filename to allow directory and file extension to be specified - Enhancements:
- DO level increased from 32 to 64. - Fixes:
- Delay exiting Recital after SYS(3) or SYS(2015)
- SET SOFTSEEK issue when search key above first record in index
- Compilation error with REPLACE command after UDF call
- FETCH INTO memvars error
- END TRANSACTION at command prompt error
- ROLLBACK locking error
- Linux ODBC Driver undefined symbol error
- RELEASE variable with same name as variable in calling program issue
- SQLCODE() issue on non-gateway data access
- Issuing two SQLEXEC() calls error
- LASTSEQNO() in workareas > 1 error
- SET RELATION to detail table in workarea 1 issue
- LIST STATUS on empty table delay
- SET AUTOCATALOG alias entries error
- ADD OBJECT in DEFINE CLASS error
- DEACTIVATE WINDOW error
- SORT error
- Other reported bugs