Re: SBS Backup failures
- From: "SuperGumby [SBS MVP]" <not@xxxxxxxxxxx>
- Date: Fri, 28 Dec 2007 22:04:25 +1100
and your tape manufacturer lies about the capacity of tape. They commonly
suggest compression ratios of 2:1, this IS NOT POSSIBLE, it is IDEAL, the
MAXIMUM compression ratio to be achieved by the technology. A 100/200 DLT
tape can take 100GB of data.
Unlike some compression processes (winzip, ARJ, etc) which analyse large
data blocks, and look at alternate compression methods to allow maximum
compression for the data, tape systems _must_ work at 'live write' speed and
inspect smaller blocks of data, compressing the data 'on the fly'. Most tape
systems actually assess the available compression (and here I'm talking
about 'hardware compression', so _totally OS/process independent_) and if it
doesn't meet specific criteria write the data uncompressed.
Tape is also what is known as 'streaming technology', part of this is that
the tape drive attempts to keep the tape moving at a constant speed past the
drive heads. LOOK at an audio cassette (if you know what they are, and can
find one :-) that you have started/stopped/fast forwarded/rewound. The tape
on the reels will have obvious 'tight' and 'loose' sections, a major
contributing factor to tape tangles. IDEALLY a tape drive will pass the tape
at constant velocity past the heads, but it also goes a step further,
sometimes rewinding the tape back _past_ good writen data then forwarding
again until the point of continuation. These two 'behaviours' sometimes
contribute to lower compression ratios (when the drive technology itself
decides 'to heck with compressing it, I'll just write it to catch up') and
also _blank_ sections of the tape if the source cannot feed data at
sufficient speed.
The various system components will affect your compression ratio. I was
BLOWN AWAY a few months ago when I changed the tape drive in a customer's
server. The new drive wouldn't talk to their older SCSI controller so we
installed a PCI-X SCSI320 controller card. Compression went from ~1.2:1 to
1.4+:1. That's 140GB on a 100GB tape, I was BLOWN AWAY.
Write a continuous stream of 10101010101010101010... to tape and you _may_
get 2:1 compression, with clean heads, a good tape (not a new one, one that
has been used enough to get the dust off it), and system components able to
maintain the 'stream' (both reading from the source and writing to the
target).
I do agree that the error message generated by NTBackup could be improved,
say 'tape full' rather than the current messsage. It is only lack of
familiarity though that led you down the path you trod, people more familiar
with the processes and technology would have seen the message and ack'd 'my
tape's full'.
"Alan C" <nospam@xxxxxxxxx> wrote in message
news:Oxkqx5ASIHA.6036@xxxxxxxxxxxxxxxxxxxxxxx
Thanks very much, everyone, for the tips below.
I've determined that the tape is filled (but not every time), so the
following conditions are true.
1. Ntbackup lies about how much it is backing up.
2. Ntbackup doesn't use either hardware or software compression, so the
tape is never used to true capacity.
3. Ntbackup is incapable of notifing the operator that the tape is full
and/or needs a second tape.
4. Ntbackup is crap.
Happy New Year to All on the KB.
"Alan C" <nospam@xxxxxxxxx> wrote in message
news:OcPyq6ARIHA.4476@xxxxxxxxxxxxxxxxxxxxxxx
Help please.
SBS backup works OK for one or two days and then fails (again once or
twice).
Backup device is internal SCSI HP 36/72 DAT
Backup log:--
12/20/2007 9:30 PM
-------------------------------
Date: 12/20/2007
Time: 9:30 PM
User: SYSTEM
-------------------------------
Backup Runner started.
NTMS session started successfully.
EnumerateNtmsObject(NTMS_LIBRARY) succeeded.
Will enumerate on 3 media libraries found.
GetNtmsObjectInformation(NtmsLibraryInfo) succeeded.
GetNtmsObjectInformation(NtmsLibraryInfo) succeeded.
Found an enabled library.
InventoryNtmsLibrary(NtmsInventoryOmid) succeeded.
Identify Media completed
EnumerateNtmsObject(NTMS_PHYSICAL_MEDIA) succeeded.
Will enumerate on 0 media types found.
GetNtmsObjectInformation(NtmsLibraryInfo) succeeded.
Found an enabled library.
InventoryNtmsLibrary(NtmsInventoryOmid) succeeded.
Identify Media completed
EnumerateNtmsObject(NTMS_PHYSICAL_MEDIA) succeeded.
Will enumerate on 1 media types found.
GetNtmsObjectInformation(NtmsPhysicalMediaInfo) succeeded.
GetNtmsObjectInformation(NtmsMediaTypeInfo) succeeded.
Found a tape media type in the library (4mm DDS).
Launching NTBackup: ntbackup.exe backup "@C:\Program Files\Microsoft
Windows Small Business Server\Backup\Small Business Backup Script.bks" /d
"SBS Backup created on 12/20/2007 at 9:30 PM" /v:yes /r:no /rs:no /hc:on
/m normal /j "Small Business Server Backup Job" /l:s /p "4mm DDS" /UM
NTBACKUP LOG FILE: C:\Documents and Settings\SBS Backup User\Local
Settings\Application Data\Microsoft\Windows NT\NTBackup\data\backup06.log
=====================<BEGIN NTBACKUP LOG FILE>=====================
Backup Status
Operation: Backup
Active backup destination: 4mm DDS
Media name: "Media created 12/20/2007 at 9:30 PM"
Volume shadow copy creation: Attempt 1.
Backup (via shadow copy) of "C: SYS"
Backup set #1 on media #1
Backup description: "SBS Backup created on 12/20/2007 at 9:30 PM"
Media name: "Media created 12/20/2007 at 9:30 PM"
Backup Type: Normal
Backup started on 12/20/2007 at 9:33 PM.
Backup completed on 12/21/2007 at 3:04 AM.
Directories: 3381
Files: 38391
Bytes: 17,368,534,090
Time: 5 hours, 31 minutes, and 26 seconds
Backup (via shadow copy) of "D: Data"
Backup set #2 on media #1
Backup description: "SBS Backup created on 12/20/2007 at 9:30 PM"
Media name: "Media created 12/20/2007 at 9:30 PM"
Backup Type: Normal
Backup started on 12/21/2007 at 3:04 AM.
Backup completed on 12/21/2007 at 4:24 AM.
Directories: 1409
Files: 21257
Bytes: 8,855,922,150
Time: 1 hour, 19 minutes, and 28 seconds
Backup of "SBS\Microsoft Information Store\First Storage Group"
Backup set #3 on media #1
Backup description: "SBS Backup created on 12/20/2007 at 9:30 PM"
Media name: "Media created 12/20/2007 at 9:30 PM"
Backup Type: Normal
Backup started on 12/21/2007 at 4:24 AM.
The requested media failed to mount. The operation was aborted.
The operation was ended.
Backup completed on 12/21/2007 at 7:55 AM.
Directories: 0
Files: 1
Bytes: 3,815,765,792
Time: 3 hours, 31 minutes, and 6 seconds
----------------------
The operation did not successfully complete.
----------------------
=======================<END NTBACKUP LOG FILE>=====================
NTBackup finished the backup with errors.
For more information about failed backups, see the article on
troubleshooting your backup at the following Web page:
http://go.microsoft.com/fwlink/?LinkId=18414
Backup ended at Friday, December 21, 2007 7:55 AM
Backup Runner finished.
.
- References:
- SBS Backup failures
- From: Alan C
- Re: SBS Backup failures
- From: Alan C
- SBS Backup failures
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