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Conference decwet::advfs_support

Title:AdvFS Support/Info/Questions Notefile
Notice:note 187 is Freq Asked Questions;note 7 is support policy
Moderator:DECWET::DADDAMIO
Created:Wed Jun 02 1993
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1077
Total number of notes:4417

477.0. "Granularity of clone deltas?" by SNOC02::WAITES (Do what it takes, take what it does) Tue Mar 28 1995 02:58

T.RTitleUserPersonal
Name
DateLines
477.1Don't worry, be happy ;-)KETJE::SYBERTZMarc.Sybertz@bro.mts.dec.com - DTN 856-7572Tue Mar 28 1995 04:387
477.2ATSE::KATZWed Mar 29 1995 12:499
477.3Cloning uses Copy On WriteNETRIX::"tsao@abelia.zk3.dec.com"Wed Mar 29 1995 18:5015
477.4Thanks & Advertise ItSNOC02::WAITESDo what it takes, take what it doesWed Mar 29 1995 21:4316
477.5testimonial?DECWET::HUNTLiz HuntTue Apr 04 1995 22:2111
477.6Cloning good, cloning with Oracle badTROOA::SOLEYFall down, go boomThu Apr 06 1995 19:1617
477.7DECWET::DADDAMIODesign Twice, Code OnceThu Apr 06 1995 20:3513
477.8request more infoDECWET::HUNTLiz HuntFri Apr 07 1995 17:2723
477.9TROOA::SOLEYFall down, go boomFri Apr 07 1995 18:1813
477.10Please post.EPS::RODERICKThe Amazing Colossal JobMon Apr 10 1995 12:345
477.11TROOA::SOLEYFall down, go boomMon Apr 10 1995 19:352
477.12db shutdown/restart - time?DECWET::HUNTLiz HuntMon Apr 10 1995 20:016
477.13TROOA::SOLEYFall down, go boomMon Apr 10 1995 23:306
477.14Don't quiesce!BIGUN::chmeee::MayneMy TARDIS isn't big enoughTue Apr 11 1995 07:1631
477.15what's the downtime wrt clonesets?EPS::HIGGINSWed Apr 12 1995 12:4925
477.16db is active while clone being backed upDECWET::HUNTLiz HuntWed Apr 12 1995 14:0725
477.17BIGUN::chmeee::MayneMy TARDIS isn't big enoughWed Apr 12 1995 21:3715
477.18Great featureEPS::HIGGINSFri Apr 14 1995 12:3316
477.19Oracle Rdb allows parallel tape backups, don't know about Oracle7CVG::PETTENGILLmulpTue Apr 25 1995 01:348
477.20DECWET::MARTINTue Apr 25 1995 13:415
477.21Oracle backup?BAHTAT::HILTONhttp://blyth.lzo.dec.comThu Nov 02 1995 07:1310
477.22Nothing's changed.. it can work, but...ASABET::swu02p.rch.dec.com::rockwellSBU NE Region Sales SupportThu Nov 02 1995 13:1212
477.23not only in-memory, but file synch. problems as wellNAMIX::jptFIS and ChipsThu Nov 02 1995 16:1518
477.24LEXS01::GINGERRon GingerFri Nov 03 1995 10:119
477.25BIGUN::chmeee::MayneIt's unhygienic.Sat Nov 04 1995 19:0313
477.26TROOA::SOLEYFall down, go boomMon Nov 06 1995 15:1310
477.27LEXS01::GINGERRon GingerTue Nov 07 1995 11:5711
477.28ASABET::swu02p.rch.dec.com::rockwellSBU NE Region Sales SupportTue Nov 07 1995 12:5210
477.29NSR + CLONE = PROBLEMS !!!BRSDVP::DEVOSManu Devos DEC/SI Brussels 856-7539Mon Apr 07 1997 11:3833
    Hi,
    
    Just to keep this stream up to date:
    
    The NetWorker (V4.2A) release notes explain that NSR is detecting the
    "sparse" files by comparing the byte length of the file (ls -l) and the
    blocks used by the file (du -k). If the byte length (converted in 1k
    blocks) is greater than the block count, NSR declares that file as a
    sparse file. So far, so well...
    
    But, NSR is reading the file to save it on tape, and when it reads the
    "hole" part of the file, it just receives blocks of null code. So far,
    so well...
    
    To correctly identify the holes during the save, NSR is "translating"
    the long sequence of null codes in its internal representation of
    "holes". So, at the restore time, the file can be correctly restore
    with its original holes. So far, so well...
    
    Now, the problem: when "du -k" is executed on an ADVFS clone, it reports
    the number of blocks really allocated to the clone (or if you prefer,
    the number of "changed" blocks in the original fileset), so ALL THE
    FILES APPEARS as SPARSE FILES TO NSR. 
    
    And, as NSR is translating the long sequence of null code into "holes",
    databases containing a lot of null-initialized areas are NOT BACKUP'ed
    as they are really but with holes.
    
    In other words, there is an obvious lack of integration between NSR and
    ADVFS, and we MUST forget ADVFS clones when using NSR... :-)
    
    Manu.
    
477.30Clone discussion suddenly switches to sparsenessRUSURE::KATZFri Apr 25 1997 15:2014
I don't think this question really belongs in this string
So if you want to discuss it further, please open a new
string.
If DECnsr doesn't figure out sparseness the same way
vdump does (by using the actual extent maps) then it will
not satisfy databases that pre-allocate blocks of zeroes
for performance reasons. I'd hope you'd follow up on that
with them. 
As discussed elsewhere in this conference, vdump uses the
maps when backing up advfs files and this allows it to
save time reading the target file, and writing to the
archive. Then later it allows a vrestore to replace the
sparseness in the same places it found it (and restores
blocks of zeroes that weren't actually sparseness).
477.31 ? ? ? ? ? BACHUS::DEVOSManu Devos NSIS Brussels 856-7539Fri Apr 25 1997 18:0824
    Thanks for your answer!
    
    You said that the discussion switch suddently to sparseness...
    
    Not exactly. I am speaking about backuping ADVFS clones on DECnsr.
    There is a lot of answers in this note stream about "BACKUP" of "CLONE"
    of "ORACLE" databases. If you are doing backups of CLONES of ORACLE
    databases then (according to the NetWorker realease notes)  you are
    very subject that your databases will be restore with "holes" which is
    NOT acceptable if they were NOT SPARSE at the backup time. The
    NetWorker release notes say that it will change with a "NEXT ADVFS"
    release. I was just trying to explain how and why  NetWorker and ADVFS
    are not understanding each other.
    
    You can say that NetWorker is responsible, NetWorker can say that ADVFS
    is responsible and WE in the field can simply return to "dump" and
    "UFS" and explain to our customer that these Engineering groups are not
    speaking to each other. 
    
    >>>    Please, try to better integrate the Digital products !!!     <<<
    
    Manu.