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Conference ssag::ask_ssag

Title:Ask the Storage Architecture Group
Notice:Check out our web page at http://www-starch.shr.dec.com
Moderator:SSAG::TERZAN
Created:Wed Oct 15 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:6756
Total number of notes:25276

6386.0. "RZ28-VW versus RZ28-VA ???" by CHEFS::OUGHTON () Mon Feb 10 1997 10:28

    I wonder if someone can help me. I work for the BPS group in the UK. A
    customer has recently run a disaster recovery test. They restored data
    from a TZ88 onto an RZ28-VA disk and the disk filled up.
    
    The Customer runs an AlphaServer 1000A 4/266 configured with a PCI fast
    wide SCSI-2 controller with 2 * RZ28-VW disks and 2 * RZ29-VW disks and
    a KZPSC PCI RAID controller. The Customer ran a standalone backup
    (booting from CD) onto a TZ88 cartridge. The customer is running
    OpenVMS V6.2-1H2
    
    For the test we supplied an AlphaServer 2100 4/275 with 1 * RZ28-VA and
    1 * RZ29-VA. When he restored his system disk to the RZ28 it filled up.
    To get over the problem quickly we installed an RZ29 which was fine.
    The question is does anyone have any ideas as to why a standalone
    backup from an RZ28-VW would fill up an RZ28-VA. I would be grateful
    for any help or pointers as to where to look.
    
    
    Thanks
    
    Dave
T.RTitleUserPersonal
Name		DateLines
6386.1I will hazard a guess...FIEVEL::FILGATEBruce Filgate SHR3-2/W4 237-6452Mon Feb 10 1997 10:449
 If the original source disk had logical entries set for some of its
 directory trees, these trees would get backed up once for each entry
 unless the backup was /image.  On restore, each of the logical entries
 becomes a physical branch and uses up physical disk space.

 Does this sound like what the customer did?

 Bruce
6386.2hmmm strange...SUBSYS::VIDIOT::PATENAUDEAsk your boss for ARRAY's...Mon Feb 10 1997 10:4611
All RZ28 family of drives (excluding the RZ28C) have the exact same goemetry.

Did the target RZ28 have other files on it at start of restore?

Did the target RZ28 have some leftover metadata after being used on a different
controller?

I can see no "drive" reason why this should have happened.

roger.
6386.3CHEFS::OUGHTONTue Feb 11 1997 04:3817
    The Customer says he did a BACKUP/IMAGE
    He also says that there were some additional data on the disk which
    wouldn't normally reside there before he did the BACKUP/IMAGE, but if
    it was on the disk before backup then it should restore OK.
    
    I wonder if the Customer is not telling me something here as the
    previous note says the RZ28-VA or -VW can still store the same amount
    of data ie. 2.1Gb
    
    I don't believe the Customer used this disk on a different controller
    previously, but I'll ask.
    
    
    Thanks
    
    Dave
6386.4Some specific things to look forSUBSYS::BROWNSCSI and DSSI advice given cheerfullyTue Feb 11 1997 08:5918
    This discussion is at too high a level for me.  The -VA and -VW have the 
    same capacity, by default, but the files may not. There are a number of 
    specific situations that can cause files on one disk to occupy a different
    size as files on a second disk.  Please do a "show device /full"
    and a "dir/siz=alloc/total" on the original disk and the backup disk 
    (the RZ28 which contains the partially restored data).  Diff the results.
    Then we can look at the simplest explanations:
    
    - Do the two disks have the same number of blocks?  Same cluster size?
    - Is the number of directories different?
    - In particular, does the restored disk have some system directories 
    	that weren't on the original, as suggested in reply .1?
    - How big are the files that didn't fit on the restored disk?
    - Which files and dirs are larger on the restored disk than on the original?
    
    Do a BACKUP/LIST of the save-set on the TZ88. What was the BACKUP
    command used?
6386.5SSDEVO::KOWALLStorageWorks Engineering SupportTue Feb 11 1997 09:2111
        -1 makes a good point with the "dir/siz=alloc/total". Or show
disk/full.

    If you initilize the two drives on two different types of controllers you
may get different capacities. So an image backup could also fail if the target
has less space.  one I know of is the HSD10. It it different from HSx
controllers.

Regards
                John