Verifying your data.

No matter how careful you are and no matter how stable your network and computer system are you should operate with the expectation that you will eventually get data corruption. This typically occurs as a result of improper shutdown of the program due to power failures in the building or inadvertently switching computers off without exiting Bookmine. It can also happen if you computer freezes. (See contents for a topic on errors and system freezes). Network problems are also a common cause of data corruption. Such events can sometimes cause data corruption..

Operating the POS while waiting for a repair on data files - Disconnected Mode

In cases where your server is not available due to maintenance or repair of corrupted data you can continue processing sales at the Point Of Sale. This is possible using disconnected mode. In this mode each POS terminal uses cached data to process sales. The sales are then posted back to the server when the data is fixed or becomes available again. See disconnected mode operation for details. You can also use this mode to process sales at external events such as trade shows and mall sales if you cannot connect to your central data.

Verification of Data integrity

Data integrity should be checked every day on the data server to ensure that you are not backing up corrupted data. This is done via the verification process.

Verification should be carried out at the end of each day on the data server. Verification is invoked automatically on closing the program each day if the verification alert cycle period is set to 1 day (This can be set for each computer from the Main Switchboard – UserOptions and entering a numeric value in the Compact alert Interval field. Set it to 1 on the server, set to 20 on clients)

Verification can be manually invoked from the Main Switchboard – Maintenance button.

Whether automatically or manually invoked you are presented with an information screen which explains the process, why it should be carried out and which files you should make sure to back up after it is finished. Please READ this screen carefully and make sure you understand its implications.

If an error occurs during the verification process a warning message will appear. If an error message appears you should print the error report for later reference (use Cut an paste or the Print command where available).

Make a normal file copy of the data file or files listed in the report as having errors and then try the repair option. Reboot the computer and retry the verification.

Repairs can cause data loss. If this fails then see the topic on repairing using an external utility.

Your primary defence against data corruption is to verify the data files regularly and back it up on success.

You can set an option that specifies how often the program will prompt you to verify your data. Note: in a multi user configuration the data is stored on the nominal Server. Nobody can be using the data during verification. The verify/compact must be carried out on the computer where the data is stored. Carrying it out on a client machine does not verify the data on the server as this could be too time consuming over a LAN. You can use the Compact Alert Interval on your Client machine as a memory aid to ensure that you go to the Server to carry out a compact there (applies only to Multi user version)

Verification should be carried out at the end of every day, before you do your backups. It is possible to have errors in a 400Mbyte data file that are not evident during a session. Backing this up can eventually mean that all your backups are faulty. Verifying the data will prevent this from happening.

A good backup strategy will involve cycling through several independent removable disks (R/W CDs are ideal. Tapes are also good), the most recent of which is always taken off site when it is completed (If the backup takes a long time and you do not wish to wait take the previous nights backup with you after starting the new backup).

Disk rotation and labeling

InfoMining strongly advises you not to label the disks with the days of the week. This is fraught with problems when a backup is skipped and a problem occurs. The backup may be more than a week old, even though it is labeled as being yesterday’s.

Use a sequence such as A, B, C, D, E, F etc or 1,2,3, etc. In addition keep a paper based log of the date and the disk that was used for the backup. Disks should be used in strict rotation. Do not skip a disk if the daily backup was skipped for some reason.

Over time your data becomes more and more important. It becomes the heart of your business. Protect it as much as possible. The operating system and programs can be reinstalled again. Your data cannot be reinstalled or reconstructed without backups. Data must be restored from backups.

External utility for repairing data files

If verification produces an error in a data file you should make a copy of that file and then try the repair option. Repairs can cause data loss. If this fails then see the topic on repairing using the external repair utility.