Section 8 TAPE INTERFACE

Transcription

1 Section 8 TAPE INTERFACE This Section describes the tape interface for backup and restore of file-save or account-save tapes. The UniVision System Administration Guide describes the mechanism for performing a FILE-SAVE or ACCOUNT-SAVE. This Section deals with the interface structure between the tape devices supported by the Operating System and used within the UniVision environment. Tape Devices Supported UniVision operates with all tape devices supported by the Operating System. The 1st step in supporting any tape device in UniVision is to set up the tape devices. The system performs :INIT-TAPE (B as a part of the initial UniVision installation procedure. This command finds the Operating System tape devices and builds 2 data file within UniVision; DEVICE-DETAILS and DEVICE-NAMES. :INIT-TAPE configures tape devices. It is possible to select and assign the devices using :INIT-TAPE. The UniVision environment cannot determine the type of tape device installed, but can determine the UNIX device names. It is the responsibility of the user to identify the tape device as a floppy diskette, cartridge tape, ½-inch tape drive, 8mm cartridge tape, CDROM device, 4mm DATA cartridge tape, etc. Note: It is not advisable to configure tape devices while the tape devices are in use. The setup function requires the reset of the tape device, therefore, use of the device during setup can result in errors and other unpredictable problems. Tape Interface 8-1

2 DEVICE-DETAILS File The DEVICE-DETAILS file contains the configuration information of each tape device. In addition, it is used for tape device attachment and locking purposes in the UniVision environment. The DEVICES file in the SYSTEM Dictionary contains the DEVICE- DETAILS file. Each user account contains a Q-pointer called DEVICE- DETAILS that point to the DEVICE-DETAILS file. Attribute Description 0 Device ID defined when setting up the tape devices with :INIT- TAPE. 1 UniVision process number of the current user using the tape device or null if not is use. 2 Tape device or device path name. 3 Default block size. 4 ERRMSG item-id used to display the type of tape device. For example, T-WHAT uses the ERRMSG number. 5 Identifies the DEVICE-ERRORS items for this device by identifying the Operating System release level. If blank UniVision assumes NCR/AT&T release Device description 7 Original device tag. 8 Block size multiple supported by the device. 9 Tape Label size supported by the device. 10 Label format, long, 512 bytes, or short, 80 bytes, if supported by the tape device. 11 UniVision label format description, displayed by T-FORMAT. 12 Current format position. 8-2 Advanced Technical Support Guide

3 Attribute Description 13 Operating System command to put the tape on-line, if applicable. 14 Start of block information, 4 spaces, then 8 nulls. 15 Operating System command to erase the tape. 16 Operating System command to format the media, if applicable. 17 Operating System command to rewind the tape media. 18 Operating System command to retension the tape media, if applicable. 19 Operating System command to unload the tape media, if applicable 20 Cascade ERRMSG item id. 21 Options used when issuing the Operating System reading from tape using the dd command. The dd utility copies the specified files from an input file to an output file. UniVision uses dd to move blocks of tape data from disk to the appropriate tape device. 22 Options used when issuing a dd command from within a UniVision tape function, that is FILE-SAVE, T-DUMP, etc. 23 Device driver type (ddi for device driver interace). Any other value means the dd command will be used. 24 Number of blocks to read per group (Windows only). 25 Initialise device (used by T-SELECT) 26 Number of blocks per group. (UniVision virtual tape). Tape Interface 8-3

4 For example, on an AT&T/NCR system under UNIX release 2.03 and UniVision release 5.1.3, the DEVICE-DETAILS items for the floppy drive are as follows: /dev/rdsk/d03ht]dev/rdsk/f0dt]/dev/rdsk/f03ht]/dev/rd sk/f03dt F inch 1.44 Mbyte (High Density)]3.5 inch 720 Kbyte (Low Density)]3.5 inch 1.44 Mbyte (High Density)]3.5 inch 72- Kbyte (Low Density) 007 F H]D]R83H]R83D 011 HIGH DENSITY]LOW DENSITY]R83 HIGH DENSITY]R83 LOW DENSITY ]...]...] tapecnt1 -d/dev/rdsk/f03ht -e]tapecnt1 - d/dev/rdsk/f03dt -e] tapecnt1 -d/dev/rdsk/f03ht -e]tapecnt1 - d/dev/rdsk/f03dt -e 016 format /dev/rdsk/f03ht >/dev/null]format /dev/rdsk/f0fdt >/dev/null]format /dev/rdsk/f03ht >/dev/null]format /dev/rdsk/f03dt >/dev/null Advanced Technical Support Guide

5 Additional Notes on the DEVICE-DETAILS File Attribute 10 defines the formats that T-FORMAT can select. Depending on the type of device this attribute might be empty. When the system selects a particular format, it determines the multi-value position in attribute 10 and uses the corresponding multi-valued position for all other attributes associated with the tape format. If there is no multi-value in a field, the system uses the first. The system stores the selected multi-valued position in attribute 12. The default value is 1. Attributes 13 to 19 contain a translation table on what commands in the Operating System execute in response to the corresponding UniVision command. Attribute 13 contains the command executed when the user enters T-ONLINE or when you insert a 2 nd reel and enter C. The following table outlines typical entries for attributes 13 to 19. Function mt command Alternate Command on-line mt -f pathname online tapecntl -d/ pathname -1 erase mt - pathname erase tapecntl -d/ pathname -e format format pathname l>/dev/null (floppy drives only) rewind mt -f pathname tapecntl -d/ pathname -w retension mt -f pathname tapecntl -d/ pathname -t unload mt -f pathname rewoff tapecntl -d/ pathname -f Tape Interface 8-5

6 O/S AT&T AIX UnixWare Note: Commands in DEVICE-DETAILS mt, resides in /usr/ucb mt tapecntl and format Attribute 5 indicates the installed version of UNIX. If the system has selected the incorrect Operating System during the initial installation procedure, tape operations are erratic and might not perform properly. You can reset the tape devices to the correct Operating System level at any time by entering :INIT-SYSTEM (B. To correct errors in the tape devices or to add a new tape device you can enter :INIT-TAPE (B. For more information refer to the UniVision Command Reference Guide. DEVICE-NAMES File The DEVICE-NAMES file contains the names of the tape devices available in the UniVision environment. This file translates the tape device number to the actual Operating System device. For example, in UniVision T-SELECT allows a user to select a tape device based on tape name. The DEVICES file in the SYSTEM Dictionary contains the DEVICE-NAMES. Each user account contains a Q-pointer called DEVICE-NAMES that points to the DEVICES,NAMES file. A typical entry in the DEVICE-NAMES file is as follows: Attribute Description 0 Device number: The ID of this file. 1 UniVision tape device number. Usually, this number is the same as the ID. It is different when a user re-orders the tape devices using :INIT-TAPE. 8-6 Advanced Technical Support Guide

7 There should be at least 1 entry for every tape device defined for use in UniVision. A typical entry is as follows: DEVICE-ERRORS File The DEVICE-ERRORS file translates messages from the result of writing to tape using dd. Based on part of the text received as the results of the previously issued dd, UniVision takes the appropriate action. Each user account contains a Q- pointer called DEVICE-ERRORS that point to the DEVICES,ERRORS file. Typical entries in the DEVICE-ERRORS file are as follows: Attribute Description 0 The key to the errors file, based on the operating system and hardware platform. The key is actually in 2 parts. The 1st part is the Operating System and hardware as defined in the following table. The 2nd part of the key is a type of operation. Only 4 operations exist: R = Read, W = Write, FR = Floppy Read, FW = Floppy Write. Attribute All Description All other attributes contain a unique set of words in value position 1, to identify an error message from the dd command. Value position 2 contains a code instructing UniVision what action to take on the error. The possible action codes are: 1 = end of data, 2 = device full, UniVision treats anything else as device not ready. Tape Interface 8-7

8 You use the following table to determine the 1 st part of the key to the DEVICE- ERRORS file: Key Part Description null NCR or AT&T UNIX Release NCR or AT&T UNIX Release 2.3 UW UnixWare Release 1.0, 1.1, 2.0 or 2.1 AIX IBM s AIX Release or 4.1 and Motorola s AIX Release 4.1. There should be 4 entries for each of these. Typical entries for NCR or AT&T UNIX Release 2.3 are as follows: 2.3R 001 Read error 002 Cannot 003 failure 004 records in]1 2.3R 001 Read error]1 002 Cannot 003 failure 2.3W 001 No such device or address]2 002 Cannot 2.3W 001 Error 0]2 002 No space]2 003 Cannot 004 Write error 8-8 Advanced Technical Support Guide

9 What Happens During Tape Device Selection When you select a tape device in UniVision, the following occurs: The system reads the DEVICE-NAMES file for the specified device name. The 1 st attribute for the device contains the ID of the appropriate DEVICE- DETAILS item. The system reads the DEVICE-DETAILS record. Attribute 5 contains the ID prefix used to determine the various tape messages. The DEVICE- ERRORS file stores the tape messages. The system reads the device error messages from the DEVICE-ERROS file. The read error messages is an item called prefix R and the write error messages is an item called prefix W. Note: If you have not selected a tape device prior to use the system attaches device 0. What Happens at Device Attachment Device attachment locks the devices selected current exclusively for UniVision. Device attachment performs the following: Reads the DEVICE-DETAILS item and verifies that another process has not locked the tape device. If there is no entry in attribute 1 of the DEVICE-DETAILS record, attaches the tape device and writes the process number to attribute 1. Tape Interface 8-9

10 The following command perform as follows: T-SELECT Utilises device selection followed by device attachment. T-ATT T-DET Utilises device attachment Removes the lock from the tape device selected currently. If DEVICE-DETAILS contains the process number, the system removes it and makes the device available for another user. T-DET U Removes the lock from the device selected currently, unconditionally. If DEVICE-DETAILS contains the process number, the system removes it and makes the device available for another user. T-FORMAT Selects the relevant format from the DEVICE-DETAILS item. Setting Up a Tape Device in UniVision to Use a UNIX File UniVision allows a user to set up a UNIX file as a tape device. You can write UniVision style tapes such as file-save, account-save, and T-DUMPs to disk by performing the following: Create an item in the DEVICE-NAMES file. Create an item in the DEVICE-DETAILS file. Create an item in the ERRMSG file, optional. The following example uses a UNIX file call taperec in the tmp directory. You can use any UNIX file name and put the information in any directory. The UNIX file does not have to exist, however, the directory must exist Advanced Technical Support Guide

11 Using the Editor, create the following item in the DEVICE-NAMES file: >ED DEVICE-NAMES UNIXFILE NEW ITEM.I 001 UNIXFILE 002.FI UNIXFILE filed In addition, create the following item in the DEVICE-DETAILS file using the Editor: >ED DEVICE-DETAILS UNIXFILE NEW ITEM.I /tmp/taperec file: /tmp/taperec F.R99/+// EOI 012.FI UNIXFILE filed Tape Interface 8-11

12 Note: You must log back to the UNIX login before your current UniVision process recognises the newly created tape/file device. To understand any messages from the UniVision environment, it is advisable to create an appropriate message in the ERRMSG file, however, this step is option and not required. Create the following item in the ERRMSG file using the Editor. >ED ERRMSG 6040 NEW ITEM >I 001 E UNIX file: /temp/taperec EOI 001.FI 6040 filed If you perform an :INIT-TAPE or :INIT-SYSTEM you must recreate the items in the DEVICE-DETAILS and DEVICE-NAMES files. Tape Conversion to UniVision You cannot restore tapes created on other Pick or Pick-like systems if the data spans more than one tape media. When saving data on a non-univision system, you must keep all the data on one tape media, otherwise, it is not possible to restore the data to a UniVision system completely. This issue only arises when you bring data from a non-univision system. UniVision does support file-saves or T-DUMP on a UniVision system across multiple tape media. Restoring UniVision Tapes on MENTOR If you are saving a UniVision account, to restore in a MENTOR system, you must use a tape label block size of 80, except for ¼-inch cartridges. ¼-inch cartridges can use any block that is a multiple of 512. Label sizes for ¼-inch cartridges can be 80 or 512 bytes. T-FORMAT sets the label size Advanced Technical Support Guide

13 Restoring Data from ADDS MENTOR Systems The ADDS MENTOR systems support 2 different file-save tape formats. The older and most common, is the original R83 save format. UniVision restores account save-tapes that are R83 compatible automatically. ADDS MENTOR release 2.8 and earlier are R83 compatible, therefor, if your system is currently on release 2.8 or earlier, performing an ACCOUNT-RESTORE on UniVision works. The newer ADDS MENTOR tape format is based on the tape utilities developed by AccuSoft Enterprises. The AccuSoft format uses a different tape of layout from R83. UniVision cannot restore account created with this format. If your system is on release 3.0 you must create the account-save tape with the R83 backwards compatibility option, using the following statement on the ADDS MENTOR: SAVE SYSTEM account-name (DFTYC The options specified save the data files, D, display the filenames, F, write the data to tape, T, check for Group Format Error, Y, and the format of the data is backwards, or R83, compatible, C. It is possible to restore an account-save tape created with this command on a UniVision system, however, the AccuSoft utility excludes all items greater than 32K automatically. The reason for the exclusion of large items is because the R83- based tape restore aborts on encountering an item greater than 32K. For all items greater than 32K you must perform a T-DUMP on the ADDS system. T-DUMP tapes made on any ADDS release are restorable on a UniVision system. UniVision save and restore supports unlimited item sizes on UniVision systems. Tape Compatibility Remember to check for tape compatibility between the new system and the system where the data resides. The new hardware might not be able to read data from an older style tape drive. The tape compatibility guidelines to be followed when upgrading your system are: Tape incompatibilities most often occur at the tape labels. The tape label can be an issue in 4 areas. Tape Interface 8-13

14 At the beginning of the 1 st tape. The 1 st label on the tape contains information on the format of the data on the tape. For example, the 1 st tape label contains the block size of the tape data and the date and time of creation. Sometimes, on an old release of software the 1 st label created is incompatible with new release software like UniVision. You can usually avoid the 1 st tape label by attaching the tape drive at the correct block size and bypass the 1 st label with a T-FWD. Between accounts Incompatibility can occur between accounts because each account starts with a tape label. It is not possible for you to assume that you can always restore data from 2 or more accounts on the same tape. The conversion is easier if you restrict the tape to one account. At the beginning of the 2 nd and subsequent reels Incompatibility can occur at the tape label on the beginning of each reel. If this occurs there is not way to correct the problem. Keep the tape data to one physical tape. In order to do this, you might have to break up large accounts on the original system. At the end of a tape reel Incompatibility can occur at the last block of data on the tape. If this occurs there is no way to correct the problem. Keep the tape data to one physical tape. ½-inch tape is the most compatible tape medium among systems. The ½-inch tape standard is well defined and followed by all Pick and Pick-like implementations, therefore, ½-inch tape is the conversion medium of choice. ¼-inch cartridge is the most problematic type tape to use for data conversions. ½- inch tapes have no standard for tape labels. Since no standard exists it is critical you keep to the tape compatibility rules outlined previously. Tapes on UniVision NT Tape operations on UniVision NT are the same as for UniVision UNIX from the UniVision users point of view. UniVision NT requires the system install to install the tape devices and drives Advanced Technical Support Guide

15 File-Save Procedure Performing the File-Save procedure sets Group locks for a long period of time. We recommend that you perform File-Saves during a period of time when you can avoid updates to the Database, however, it is possible to perform a File-Save while updating the Database. The File-Save does not use the Item lock table to perform the save, therefore, processes that have Item locks set do not block the File-Save process. The File-Save process respects any Group locks set by the system while setting or removing an Item lock. Since Item locks set a Group lock for very short periods of time, the effect of setting an Item lock does not stop or impede the progress of the File-Save. File-Save Process The easiest way to describe the File-Save process is as follows: 1. Save all the non D-pointer, data, in the SYSTEM File. 2. Build a list of all the accounts defined in the SYSTEM File. 3. Save the Account s Master Dictionary. 4. Save the Dictionary File. 5. Save the Data File. In real terms, it is slightly more complicated. The following explains the logical order of saving the Database to tape, without describing how the system formats the data on the tape in detail. The File-Save begins by saving the data information contained in the SYSTEM File, step 1, and building a list of all accounts, step 2. For the SYSTEM file only, it collects all data items, such as Q-pointers and puts them at the beginning of the tape before searching for data pointers. Once it has built the list, it saves the data in the Account s Master Dictionary, step 3. During the File-Save of the Master Dictionary, if it encounter a D-pointer to a Dictionary file, the File-Save starts saving the Dictionary file and returns to step 3 when it has saved the complete Dictionary. During the File-Save of the Dictionary file, if it encounters a D-pointer to a Data file, the File-Save starts saving the Data file and returns to step 4 when it has saved the complete Data file. Tape Interface 8-15

16 During this process SAVE sets Group locks in all 4 file levels based on the Group the process is formatting currently to tape. SAVE sets a maximum of 4 group locks, one in each of the file levels, SYSTEM, Account Dictionary, Data Dictionary and Data File. SAVE respects Group locks but ignores application or Item locks. Note: UniVision allows updates to the database when File-Save is active. Be aware that updating the database performing a File- Save might compromise the saved data s referential integrity. Since the File-Save only uses Group locks, application software continues to function while SAVE is in process, however, the application might have to wait when setting a Group lock depending on where the system requires the lock. The system sets a Group lock in the SYSTEM file during the initial save of the SYSTEM data and the building of the list of accounts to save. It should release any required Group locks very quickly, since applications do not update the SYSTEM file in practice, this is not an issue. The system sets a Group lock in the Master Dictionary for an extended period of time, while it saves the Dictionary and Data file in the accounts. It is possible to avoid this issue if the application does not update the Master Dictionary, otherwise the process might have to wait an extended period of time before setting a Group Lock. The system sets the Dictionary file lock for a shorter period of time while it saves the Dictionary file data. If an application does not update the Dictionary file, no conflicts are possible, otherwise the process might have to wait an extended period of time before setting a Group Lock for a dictionary item. The system sets the Data file lock for very brief periods of time. The File-Save process only stops updating of Data files briefly. Note: You should change tapes quickly because all Group locks remain in place until the process continues Advanced Technical Support Guide