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.RIGHT;VAX/VMS
.RIGHT;Disk#Backups
.B 3.C;Software Documentation Memo No_. 52.1
.B.C;^&Public&#Disk&#Backups&#with&#the&#VMS&#BACKUP&#Utility\&
.B.C;Frank J. Nagy
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.B.C;$$Month#$$Day,#$$Year
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.STYLE HEADERS 6,0,7
.HL1 Introduction
.BR.P;
Before the VMS V2.3 maintenance update, the only program available for
saving the public (both system and user) disks was the DSC2 utility.
However, using DSC2 required the system to be shutdown or the user disk
to be dismounted.  With VMS V2.3, the VMS BACKUP utility was made
available.  BACKUP provides a much better utility to backup and restore
the disks than DSC2.  Some of BACKUP's advantages over DSC2 are:
.LIST ,"-"
.LE;Able to perform the file saves online (no need to stop timesharing).
.LE;Able to exclude selected files from being saved so that temporary or
known active files need not be saved.  In the case of the system disk,
the paging and swapping files need not be saved leading to a vast reduction
in the required amount of tape.
.LE;More efficient use of tape by using a large physical block size on tape.
.LE;Better detection and recovery from tape errors.
.LE;Able to do selective restore of particular files from tape (without
having to copy the entire tape set to a scratch disk to restore a single file).
.LE;Able to perform incremental saves of recently change files.
.END LIST
With the release of VMS V3.0, BACKUP (and some cooperative aspects of the
Files-11 file system) was enhanced considerably to the point where DSC2
is no longer used at all.  In fact DEC plans to drop support of DSC2 with
release of VMS V4.0 (sometime next year?).  BACKUP is used on the
ACNET systems (with the /IGNORE=|INTERLOCK qualifier) to save the public
disks without stopping normal timesharing or control system operations.
.BR.P;VMS BACKUP is useable as a DCL command, it is described in the ^&VAX/VMS
Utilities Reference Manual\&.  In order to simplify and control the
normal activities of preparing backups of the public disks on the ACNET
VAX's, a set of command procedures was created which internally use the
VMS BACKUP command to perform the disk saves.  A different form of the
BACKUP command was then created for the OPERATOR turnkey account
(see Software Documentation Memo No_. 44.1) to use these command procedures.
.HL1 Full Disk Backup
.BR.P;A full disk backup of all the Development System disks is
done on a weekly basis.  Each full disk
backup saves all the files on a particular disk.  Each disk volume
has two sets of tapes to be used for the full disk backup (alternating
between the sets).
For each file saved by BACKUP, the date and time are recorded in the
on-|disk
file header in the field reserved for the date and time the file was last
saved.
.BR.P;
A similar full disk backup is done daily for the Operational System
disks, except that the Operational backups are done disk-|to-|disk rather
than disk-|to-|tape since the Operational System uses removeable media
disk drives for its system and user disks.  These backup disks permit the
Operational System to be quickly brought back into operation following
the failure of a disk drive or the crashing of a disk pack.
.BR.P;An online full disk backup is requested by using the
operator command BACKUP.  The format of the command for a full disk backup is:
.B.I+10;^&OPR>\&BACKUP/FULL disk-set
.B;where the parameter (disk-set) identifies which disk volumes are to be
saved.  If the parameter is not given, the disk-set will be prompted for.
The recognized disk sets are:
.B.LM+14.TAB STOPS 17
.BR.I-9;ALL	backup all the disks (both system and user).
.BR.I-9;SYSTEM	backup just the system disk.
.BR.I-9;USER1	backup just the first user disk (given by the logical name
USR$DISK1 on the Development System and the name OP$USR1 on the Operational
System).
.BR.I-9;USERn	backup just the nth user disk (given by the logical name
USR$DISKn on the Development System and the name OP$USRn on the Operational
System).
.BR.I-9;USERS	backup all user disks, but not the system disk.
.B.LM-14
The OPERATOR BACKUP command qualifiers /DISK and /TAPE determine if the
backup output media is to be a disk pack or magnetic tape.  The /DISK
qualifier may currently only be used on the Operational System (where
it is the default).  The /TAPE qualifier is the default for the Development
System).
.BR.P;
When multiple disk volumes are specified by the disk-set parameter
of the BACKUP operator command (see above), the files on each disk volume
are saved by separate BACKUP utility operations.  Thus the command
.B.I+10;BACKUP/FULL  USERS
.B;is equivalent to the series of commands
.B.I+10;BACKUP/FULL  USER1
.BR.I+10;BACKUP/FULL  USER2
.BR.I+10;...
.BR.I+10;BACKUP/FULL  USERn
.B;in its action.  If ALL is specified as the disk-set parameter, then
the command is equivalent to multiple BACKUP commands, the first specifing
the SYSTEM disk and the rest the user disks.
.HL2 Disk-to-Tape Backups
.BR.P;
The qualifier /ONETAPE may be used with the BACKUP/FULL/TAPE command
If /ONETAPE is not used, the
command procedure will attempt to allocate and use two magtape drives (if
both tape drives are available).  The /ONETAPE qualifier is used to force
the use of only a single magtape drive for the save operation (leaving
the other available for users).
The error message:
.B;%ONLBAKFUL-F-NOTAPES, all tape drives are currently in use.
.B;will result if no free tape drives are available.  The BACKUP command
should be retried after the current users are finished with the tape
drives.
.BR.P;
After allocating the
tape drive(s), the command procedure will ask for the first tape(s) to be
mounted.  BACKUP will, when using two tape drives, automatically
switch from one tape drive to the other when finished with the tape mounted on
the first drive.  The command procedure will wait for you to reply to
a prompt to indicate that the tapes have been mounted and that the backup
operation can proceed:
.B.I+10;Ready to proceed [type Y or YES]?
.B
If the answer to the prompt is Y (or YES) then the procedure will begin
the save operation.  If the answer is EXIT then the procedure will exit
back to the OPERATOR command prompt or to the next disk-|set save operation.
Any other answer will cause the procedure to respond with the same
prompt.
.BR.P;The backup operation will proceed automatically after the tapes
are mounted.  The files will be saved onto the tape, the tape will be
rewound, and then a verification pass will be made to compare the tape
contents to the disk contents.  BACKUP will switch to the second tape
(if needed) after the verification pass on the first tape is completed.
If only a single tape drive is being used, BACKUP will prompt you to mount
the next reel of tape (if needed) with the messages:
.B
.BR;%BACKUP-I-RESUME, resuming operation on volume 'n'
.BR;%BACKUP-I-READYWRITE, mount volume number 'n' on 'dv' for writing
.BR;Press return when ready:
.B;which specify the tape volume number (n) and the magtape drive
(dv) on which it is to be mounted.  The same messages will be used
if two tape drives are being used and the third tape (for instance) is
not mounted when required by BACKUP.
BACKUP will output the "%BACKUP-|I-|RESUME" message even if the next
reel is already mounted and requires no operator intervention.
The completion of the BACKUP operation for a particular volume is
signalled by:
.B.I+10;Backup of 'volume' has been completed.
.B;If multiple disk-sets are being saved this will be followed by a
request for the first tape volume of the next disk-|set.
.HL3 Tape Volume Labels
.BR.P;The tape volume labels for the full backup tapes (first tape in
a tape set) are FBSYST, FBUSR1, and FBUSR2 for the
Development system and user disks respectively.
The equivalent tape volume labels for the Operational system and user disks
are OPSYST and OPUSR1 (currently).
Additional tape volumes in a tape set have labels
given by replacing the last two characters of the above names by 02, 03, and
so forth.  
.HL3 Tape Error Messages from VMS BACKUP
.BR.P;
The %BACKUP-F-|WRITENABLE
error indicates that the tape was mounted without a write-|enable ring
inserted; just correct the problem and retry the BACKUP command.
Similarly, the fatal error %BACKUP-F-|LABELERR
indicates that an I/O error occurred
during the tape label processing.  In such a case, a different tape should
be used when the command is retried as the original tape probably has a bad
spot at the start.  The %BACKUP-W-|SOFTWERRS message issued at the completion
of the writing of a tape volume provides a count of "soft"
write errors that occurred.  If this count becomes too large
(greater than 25 or so), the tape
should be replaced before the tape set is reused for another backup.
.HL2 Disk-to-Disk Backups
.BR.P;
The disk-to-disk backups proceed in a fashion similar to the disk-|to-|tape
backups discussed above.  The operator is informed which disk volume is
being saved and onto which disk drive the backup disk pack should be
mounted.  Since only RM03 drives have removeable disk packs (in the ACNET
system), the message:
.B;%ONLBAKDSK-F-NODRIVES, no disk drives of required type are available
.B;will result if a free drive cannot be found.  If a free drive is found
but not available for usage (has been marked /NOAVAILABLE, see the
OPERATOR command DEVICE in 
Software Documentation Memo 44.1), then the message printed is:
.B;%ONLBAKDSK-F-DRVNOTAVL, disk drive for backup not available
.B;Once a drive has been found the procedure prints a message requesting
the backup volume be mounted and then prints the prompt:
.B.I+10;Ready to proceed [type Y or YES]?
.B
If the answer to the prompt is Y (or YES) then the procedure will begin
the save operation.  If the answer is EXIT then the procedure will exit
back to the OPERATOR command prompt or to the next disk-|set save operation.
Any other answer will cause the procedure to respond with the same
prompt.
The save operation then proceeds very much as for disk-|to-|tape backups
(except for the need to mount additional reels of tape) until completion
as signalled by a completion message as show above.
.HL2 VMS BACKUP Verification Errors
.BR.P;BACKUP will indicate the start of the verify pass on a tape with
the STARTVERIFY message:
.B;%BACKUP-I-STARTVERIFY, starting verification pass
.B;Files copied in a disk-to-|disk operation are verified one-|by-|one after
each is copied.
Some errors
will occur because the BACKUP operation is done online and users may
create, modify, or delete files while BACKUP is running.  Some of these
type of errors are %BACKUP-E-|CONTINUE, %BACKUP-E-|EOFMISMATCH,
%BACKUP-E-|FIDERROR,
%BACKUP-E-|OPENDIR, and %BACKUP-E-|VERIFYERR and can usually
be ignored as the files affected
will be saved by the next incremental backup (see below).
.HL2 Tape Saveset Names
.BR.P;
Each full backup tape set will contain one BACKUP saveset whose name is
given by the volume name of the system disk (currently DVSYSRL3.BCK for
the Development system disk) or a modified form of the logical name for
the user disk device (i.e., currently USRDISK1.BCK and USRDISK2.BCK for
the Development user disks).  The Operational system disk saveset is named
OPSYSRL3.BCK and the user disk saveset is named OPUSR1.BCK.  As more
user disks are added to the Development and Operational systems, the
same progression of names will be retained (USRDISK3, USRDISK4, .._. for the
Development system and OPUSR2, OPUSR3, .._. for the Operational system).
.HL1 Incremental Disk-to-Tape Backup
.BR.P;An incremental disk backup of the Development system disks
is done on a daily basis.  This type
of backup will save on tape copies of those files which have been created
or modified since the date of their last backup.  Each full or daily
incremental
backup operation records the current date and time in the
on-|disk file header of
each file that has been saved.  The use of the incremental backup insures
that a relatively recent (within a day) copy of each file is saved
without requiring a large
amount of time to generate disk backups.
.BR.P;Many of the comments about the full disk backup command procedures
also apply to the incremental backup command procedures.  The operator
command to start an incremental backup is:
.B.I+10;^&OPR>\&BACKUP/INCREMENTAL
.B;with no parameters.  The command procedure will allocate and
use only a single tape drive since only a single tape should be required for
the incremental backup of all the disks.  Files from the system disk and
all user disks are
saved on the same tape in separate BACKUP savesets.  The names of the savesets
are the same as those used for the full backup tape savesets (see above).
.BR.P;The command procedure will ask you the following question before
requesting the mounting of the tape:
.B.I+10;Is this a normal daily incremental backup [Y/N]?
.B;If you are doing the normal daily incremental backup answer this question
with "Y" or "YES" so that the day code (ddd) will be set to the first three
letters of the day of the week
("MON", "TUE", "WED", "THU", "FRI", "SAT", or "SUN").
If you answer "N" or "NO", the assumption is made that a special incremental
save is being performed (i.e., before a power outage) and the day code is set
to "SPC".  The tape volume label for the Development System incremental save
is formed from the characters "IS" (for
Incremental Save) and the day code.
An incremental save of the
Operational System replaces the "IS" in the tape volume label with "OS".
For normal daily backups, the tape
volume labels are of the form "ISddd"; for special incremental backups,
the tape volume label is given by "ISSPC".
Note that a special incremental save will not change the backup date and
time in the file headers so that the same files will be saved by the next
daily incremental backup.
.BR.P;The command procedure will ask that you mount a particular save tape
volume on the selected magtape drive.  The command procedure will continue
with the operation after you reply to a prompt that the
tape is mounted on the drive.:
.B.I+10;Ready to proceed [type Y or YES]?
.B
If the answer to the prompt is Y (or YES) then the procedure will begin
the save operation.  If the answer is EXIT then the procedure will exit
back to the OPERATOR command prompt or to the next disk-|set save operation.
Any other answer will cause the procedure to respond with the same
prompt.
After the save operation is completed the message:
.B.I+5;Finished with incremental backup tape on 'device'
.B;is printed on the system console.
The incremental backup operation is then complete.
.HL2 Excluded Files
.BR.P;Various files are excluded from incremental backups (full backups
use the /IMAGE qualifier of the VMS BACKUP command).  Some of
these files are excluded because the files are always open and active when
the system is running (the error log file).  Other files
are not saved because there is no point in saving those files (the paging
and swapping files which have had a "SET FILE/NOBACKUP" done on them).
Lastly, some files are not saved because they are
directory entries that point to files that are also entered in 
some other directory ([RSXLIB], [SYSLIB] and [1,1] for example).
.BR.P;The following files are excluded from incremental
backup saves for all disks and
all directories:
.B.LM+20.TAB STOPS 23
.I-12;*.LOG	assumed to be log listings for batch jobs and forked command
lines.  These are assumed to be actively open for output or left on the disk
by a batch job that was setup to not generate any paper printout.
.B.I-12;*.TM%	assumed to be temporary files usually with file types *.TMP
(general temporary file) or SOS%%%.TM1 (SOS editor temporary file).
.B.I-12;MAP.DIF	assumed to be a temporary file used by the DIFFERENCES command.
.B.LM-20
In addition, all files with file type .SYS are not saved
from the MFD (directory
[0,0]).  This is done to prevent the index file (INDEXF.SYS) from generating
lots of verification errors because the /RECORD qualifier of the BACKUP utility
caused the file headers (in the index file) to be changed.  Also, the
bad block files (BADBLK.SYS and BADLOG.SYS) in the MFD are never saved.
.BR.P;On the user disks, no files in the directories [1,1] and [SYSLIB] are
saved.  These directories are assumed to be entries in the MFD that point
to some other directory.  Currently this is only 
effective for [RSXLIB] on USR$DISK1 on the Development System.
Files in [RSXLIB] (and its subdirectories)
will only be saved once and will be marked as coming from
[RSXLIB].
.BR.P;On the system disk several more directories are excluded from the
save since they are just MFD entries that point to another directory.
Included in this list are [SYSMAINT]*.* and [SYS%.00%00%]*.*.
In addition, several additional files are excluded from the system disk saves
either because they are always open for writing or because they need not be
saved.  The system error log file, ERRLOG.SYS, in [SYS%.SYSERR] is excluded
from the incremental save because it is open for writing.
The list of excluded files may be modified in the future as more experience
is gained with the BACKUP utility and the incremental backup ability.
.HL1 Default Backup Command
.BR.P;
The normal daily backup operation is invoked by the OPERATOR command:
.B.I+10;^&OPR>\&BACKUP
.B;This becomes a "BACKUP/INCREMENT" OPERATOR command on the Development
System and a "BACKUP/FULL/DISK" on the Operational System.
.HL1 Backup Journals
.BR.P;
The list of files saved onto a tape is added to BACKUP journal files
stored under logical name SYS$BACKUPS.  This is currently done only for
the Development System (on a regular basis) as the disk-|to-|disk saves
for the Operational System are not journalled (the output disk volume is
essentially an exact replica of the original).  The journals permit one
to locate a particular file in a collection of full and incremental tape
volumes.  This is very helpful when trying to locate a particular file to
restore it (saves searching the tapes themselves).
.BR.P;The file names of the journal files are the same as the tape save
set names (see above).  The file types are the VMS BACKUP defaults of .BJL.
The journal files may be examined by doing:
.B.I+10;BACKUP/LIST/JOURNAL=SYS$BACKUPS:filename
.B;where the VMS (not the OPERATOR) BACKUP command is used.  Additionally,
a command procedure has been written to simplify finding a file or set of
files in the current save tapes for a disk:
.B.I+10;@SYS$MGR_UTIL:FNDSAVFIL  disk  select
.B;where the disk parameter specifies which disk using the "SYSTEM" keyword
for the system disk and "USERn" for a user disk (alternatively, the user disk
logical name, such as USR$DISKn, may be used).  The select parameter is
a list of one or more file and directory specifications
(separated by commas if more than one specification)
to be searched for in the journal file (the select parameter is used to form
the /SELECT option of VMS BACKUP).  Future enhancements will probably include
the creation of an OPERATOR RESTORE command to restore single files (or small
sets of files) from tape.
.TEST PAGE 20.B 5.TAB STOPS 20
^&Distribution\&
.B.NO PERIOD
##Normal
.BR;##Operations Group
.BR;##E. Anderson
.BR;##B. C. Brown
.BR;##K. Eng	MS 120
.BR;##L. Klein
.BR;##F. Mehring
.BR;##D. Ritchie	MS 120
.BR;##D. Quarrie	MS 223
.BR;##K. Schuh
.BR;##J. Tinsley
.BR;##file
.B4
fjn: USR$DISK1:[NAGY.DOC]DOBACKUPS.RNO