When adding new media to a tape library, you can always just put the media into unused storage slots using the importmedia CLI command, and then run "check_inventory -l /dev/sg# -f" to find that new media and internally label it.
However, sometimes you need to just put one piece of media in a library, or you just want to check the label written on a tape with the barcode affixed to the tape cartridge, or you want to overwrite the internal label on the tape.
KEEP IN MIND: If you overwrite the internal label on a tape, all files stored on that tape will be permanently lost.
There is an option to the "tape_inv" command to check just one piece of media. If you run "tape_inv -l /dev/sg# -v VOLUMENAME -d drivename", substituting the volume name you wish to check, OSVault will search the library storage slots and import slots for that barcode label, and then will load that tape cartridge into the first drive and check for an internal tape label. You must specify the drive name of the first drive, found in the output of the "listdrives" command.
Without any other options, running this command will just load the tape cartridge, read the internal label, and then return the tape to the storage/import slot it came from.
If you specify the "-f" flag to tape_inv, such as "tape_inv -l /dev/sg# -v A000001L5 -d /dev/st1 -f", the media will be loaded, and if not already labelled it will be labelled internally with the same label as the barcode on the outside of the tape cartridge. This option might be easier to use than the "check_inventory" command at times.
If you wish to recycle an empty tape, you can use the "tape_inv" command to overwrite the existing label with a new label, with the "-f -x -x" option. The two "-x" flags are required to indicate that you really mean to do this destructive operation. Once this command completes, the tape media is empty in that cartridge, and future writes will start at the beginning of the tape. It is also necessary to reset the tape cartridge's database entry to start using that tape again. A command such as
mysql -e "update archive.media set Free_Space=\"1666704934\" where Label=\"A00001L5\""
will set the free space on the tape to the default for LTO-5 media.
This tape_inv option is available in version 4.1.7 and later of OSVault.
Future releases of tape_inv will allow you to run the command when other tape operations are active and will not require you to specify the device name for the first tape drive.
Monday, March 19, 2012
Wednesday, March 7, 2012
Recovering OSVault Archived Files Directly From Tape
There are several situations that can occur that will require you to recover files directly from a piece of magnetic tape, rather than through the disk cache. These include:
- Loss of the disk cache and related database due to catastrophic failure such as fire or damage
- Export and movement of tape cartridge(s) to another location and desire to import those tapes
- Recovery of previous versions of files that may have been overwritten after initial migration
This post will cover the methods to accomplish the last situation: scanning a tape and recovering all the files on that tape that may have been overwritten later.
Recovering Old Versions Of A File
Recovering an old version of a file can be the most tedious process if you do not know exactly when that version was overwritten. OSVault keeps a history of the last time that a tape cartridge was mounted, so that information can help to reduce the number of tapes that must be scanned to find an old file.
To scan a tape and recover all the files on that tape back to disk, you use the "tape_dump" CLI command. There are two ways to recover files from that tape, either as "stubs" or as whole files. There are different reasons to use each option. A "stub" recovery, using the "-s" option to "tape_dump", will create a stub file in the OSVault maintained file system but will not read in all the data portion of that file until that file stub is read later. This allows you to import an entire tape while only using a small amount of disk storage. Then you can browse the files recovered, and copy/use only the file(s) desired, while not reading all the other undesired files into disk storage.
You can also recover all files directly from a tape onto disk storage. This would be used if you are reading a tape into a non-OSVault file system or if you know you need all files stored on a particular tape. Keep in mind that LTO-5 tapes can have 1.5TBytes of more of files on them.
If you are on an OSVault system, you can use the "-v" option to the "tape_dump" command to have the robotics load the select tape cartridge volume into an unused drive for recovery. Other operations can be active on the OSVault system at the same tape, such as migration and staging. So, if you wish to recover the stubs of all files on tape A0000325L5 to an OSVault cache directory called "/cache/recovered_files", you would use the CLI command;
tape_dump -v A0000325L5 -s -f /cache/recovered_files
This will cause the tape to load into a drive, when a drive is available, and to scan the tape and create a stub in the directly /cache/recovered_files for every file it finds on the tape. After the tape_dump completes, or is killed with a control-c, the files can be displayed with either the web browser, file browser or command line, and the desired file can be retrieved by copying or reading the file. That reading/copying of the file will reload the tape in the drive and initiate a staging operation, bringing all the data portion of the file back into disk cache.
- Loss of the disk cache and related database due to catastrophic failure such as fire or damage
- Export and movement of tape cartridge(s) to another location and desire to import those tapes
- Recovery of previous versions of files that may have been overwritten after initial migration
This post will cover the methods to accomplish the last situation: scanning a tape and recovering all the files on that tape that may have been overwritten later.
Recovering Old Versions Of A File
Recovering an old version of a file can be the most tedious process if you do not know exactly when that version was overwritten. OSVault keeps a history of the last time that a tape cartridge was mounted, so that information can help to reduce the number of tapes that must be scanned to find an old file.
To scan a tape and recover all the files on that tape back to disk, you use the "tape_dump" CLI command. There are two ways to recover files from that tape, either as "stubs" or as whole files. There are different reasons to use each option. A "stub" recovery, using the "-s" option to "tape_dump", will create a stub file in the OSVault maintained file system but will not read in all the data portion of that file until that file stub is read later. This allows you to import an entire tape while only using a small amount of disk storage. Then you can browse the files recovered, and copy/use only the file(s) desired, while not reading all the other undesired files into disk storage.
You can also recover all files directly from a tape onto disk storage. This would be used if you are reading a tape into a non-OSVault file system or if you know you need all files stored on a particular tape. Keep in mind that LTO-5 tapes can have 1.5TBytes of more of files on them.
If you are on an OSVault system, you can use the "-v" option to the "tape_dump" command to have the robotics load the select tape cartridge volume into an unused drive for recovery. Other operations can be active on the OSVault system at the same tape, such as migration and staging. So, if you wish to recover the stubs of all files on tape A0000325L5 to an OSVault cache directory called "/cache/recovered_files", you would use the CLI command;
tape_dump -v A0000325L5 -s -f /cache/recovered_files
This will cause the tape to load into a drive, when a drive is available, and to scan the tape and create a stub in the directly /cache/recovered_files for every file it finds on the tape. After the tape_dump completes, or is killed with a control-c, the files can be displayed with either the web browser, file browser or command line, and the desired file can be retrieved by copying or reading the file. That reading/copying of the file will reload the tape in the drive and initiate a staging operation, bringing all the data portion of the file back into disk cache.
Monday, March 5, 2012
Exporting Tape Cartridges from an OSVault-Managed Tape Library
This posting is meant to just outline the steps you must follow to export an infrequently-used tape cartridge from your tape library that you wish to store on the shelf. That shelf-stored (absent) tape cartridge is then not accessible for restoring files, but you will get notified if it is required.
Selecting a Tape To Export
Obviously, you probably don't want to export a tape cartridge that is used frequently. If you export a tape cartridge that is needed by the system, the request for the file on that tape cartridge will get an error and you will need to do some manual steps to rectify the situation.
There is a report called "Offline Media Report that will try to find "copy2" volume-group media to export, and also to tell you the least recently used tape cartridge media. You can run the report by clicking the "Run Now" button as shown below. The click the "Reports" menu icon to reload the page and look for your report in the "View Reports" side menu.
In the report, select a tape you wish to export. Then proceed to the next step.
Exporting a Tape
First, don't just open the library and pull a tape out. OSVault won't know what you did and will have a real problem correcting the situation. You should use the "Media" menu icon and click the Label button of the tape you wish to export, such as tape A00425L4 in the example below.
Once you click on the tape button, another web-browser window will open with the tape cartridge information. Just click the "Export Volume" to move the tape cartridge into the I/E slot (sometimes called the I/O slot) of the library. This will also mark the media as "absent" in the OSVault database, so that requests for files only on that tape cartridge will be returned as an error, and the "Export Media Requests" subwindow will be able to display the status (that the cartridge needs to be imported).
Once you click on that button, the tape cartridge will be in the library import/export slot. You can then open that slot (how you do this depends on the library model) and remove the tape.
Importing A Shelf Tape Cartridge Back Into the Library
Importing a absent tape cartridge is relatively simple. You just put the cartridge you desire to import back into the Import/Export slot of the tape library, then go to the "Media" menu icon screen, click on the tape volume you just put into the I/E slot, and then click "Import Volume". OSVault will then go to the import/export slot, verify that the correct tape is there, then move it to an open storage slot and change the database to show that the tape is now "resident". Keep in mind that there must be at least one empty storage slot in the library to move the tape to, and that empty storage slot can't be the one that was just used by a tape that is presently in the drive.
What If You Don't Want to Export The Least Recently Used Volume
In some cases, you might have a directory that is all in one volume group and you want to export those tapes that have those files, since you won't be reading them again for a while. In that case, use the "File Location Report" option in the Report menu icon screen to get a full list of all files and what tapes they are on. You can then use your browser tools to locate the files you wish and get a list of the tapes they are on, then export those tape cartridges using the above steps.
How Do I Know If A File is Requested From An Absent Tape Cartridge
There is a browser window you can open that updates continually, and will print out a requested "absent" tape cartridge label when needed. The following shows what that screen looks like. You open that browser window by clicking the "Export Media Requests" button on the "Media" screen.
Selecting a Tape To Export
Obviously, you probably don't want to export a tape cartridge that is used frequently. If you export a tape cartridge that is needed by the system, the request for the file on that tape cartridge will get an error and you will need to do some manual steps to rectify the situation.
There is a report called "Offline Media Report that will try to find "copy2" volume-group media to export, and also to tell you the least recently used tape cartridge media. You can run the report by clicking the "Run Now" button as shown below. The click the "Reports" menu icon to reload the page and look for your report in the "View Reports" side menu.
In the report, select a tape you wish to export. Then proceed to the next step.
Exporting a Tape
First, don't just open the library and pull a tape out. OSVault won't know what you did and will have a real problem correcting the situation. You should use the "Media" menu icon and click the Label button of the tape you wish to export, such as tape A00425L4 in the example below.
Once you click on that button, the tape cartridge will be in the library import/export slot. You can then open that slot (how you do this depends on the library model) and remove the tape.
Importing A Shelf Tape Cartridge Back Into the Library
Importing a absent tape cartridge is relatively simple. You just put the cartridge you desire to import back into the Import/Export slot of the tape library, then go to the "Media" menu icon screen, click on the tape volume you just put into the I/E slot, and then click "Import Volume". OSVault will then go to the import/export slot, verify that the correct tape is there, then move it to an open storage slot and change the database to show that the tape is now "resident". Keep in mind that there must be at least one empty storage slot in the library to move the tape to, and that empty storage slot can't be the one that was just used by a tape that is presently in the drive.
What If You Don't Want to Export The Least Recently Used Volume
In some cases, you might have a directory that is all in one volume group and you want to export those tapes that have those files, since you won't be reading them again for a while. In that case, use the "File Location Report" option in the Report menu icon screen to get a full list of all files and what tapes they are on. You can then use your browser tools to locate the files you wish and get a list of the tapes they are on, then export those tape cartridges using the above steps.
How Do I Know If A File is Requested From An Absent Tape Cartridge
There is a browser window you can open that updates continually, and will print out a requested "absent" tape cartridge label when needed. The following shows what that screen looks like. You open that browser window by clicking the "Export Media Requests" button on the "Media" screen.
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