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H_Sharma's avatar
H_Sharma
Level 6
10 years ago

SCSI Reserve and Mount Point

Hello Experts,

Pls help with the 2 points.

1)Difference between SPC-2 SCSI reserve and SCSI persistent reserver. What are these?

2) Lets say we have two mount points in backup selection with multistream enabled in backup selection and in Policy.
   \exchange, \firewall now we exclude this firewall mount point directory in exclude_list.
So what will happen. Job for firewall would start or get failed? How many jobs would run?

 

Thanks,

7.6
Backing Up
Backup and Recovery
Basics
NetBackup
Windows Server (2003-2008)
  • mph999's avatar
    mph999
    10 years ago

    Number 2, you can research yourself, give it a go, and report back what you find.

    Number 1 I will help with, again you can also check the guides.

    SCSI SPC-2 reserve is quite basic - a reservation is just put on the drive, for example by media server1.  This prevents any other HBA from making a reservation on the drive (yes reservations 'come' from the HBA, so the drive is therefrore reserverd.  The only way for the reservation to be released is for a scsi reservation release to be sent to the drive, from the same HBA, or by powercycling the drive.

    This is fine, apart from if say you had a cluster and the machine using the drive fails.  Another machine takes over but cannot release the drive, as this can only be done by the original HBA.

    Persistent  is more advanced, basically a reservation key is used, which using various utilities can be read from the drive itself - it looks like this:

    dr-media1:/usr/openv/netbackup/logs/bptm # sg_persist --read-reservation -d /dev/sg5
      IBM       ULT3580-TD5       0103
      Peripheral device type: tape
      PR generation=0xb, Reservation follows:
        Key=0x1d00006001e8488
        scope: LU_SCOPE,  type: Exclusive Access

    The main difference with this, is that if the key is read, it can be determined 'who' set the reservation.   I'm not sure how, but I am told Engineering are able to determine if NBU 'made' the key.  WHat this means is that if the original server, say media server1 set the reservation, a different media server can release it, providing NBU made the reservation. 

  • Marianne's avatar
    Marianne
    10 years ago

    Please read through the section in the manual that I have referred to above.

    There is a section under this topic:

    Recommended use for Enable SCSI reserve property

    You will see that SCSI persistent reserve is especially important in your environment where your clustered master server nodes have tape drives attached.
    You recently posted when there were issues with tape drives after master server failover.

    To know if your tape drives support SCSI persistent reserve, check the NBU HCL:  http://www.symantec.com/docs/TECH76495

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  • Marianne's avatar
    Marianne
    Level 6
    10 years ago

    You need to check tape drive compatibility, not tape library.

    You have deleted the Enquiry String output in scan command in one of your other posts, so, we cannot help with checking the HCL.

    Oh... I have just checked the HCL - it does not list SCSI Reserve support.
    You will need to check with the hardware vendor.
    STK can have HP or IBM tape drives.

    See this note in the HCL:

    3. Symantec recommends the use of SCSI Persistent Reserve (SPR) whenever all the hardware in your device path supports it. Refer to the NetBackup Administrator's Guide for more information on SPR and the types of configurations where SPR may be more effective than the default SPC-2 SCSI reserve and release method.

  • H_Sharma's avatar
    H_Sharma
    Level 6
    10 years ago

    Hi Marianne,

     

    Pls find.

     

    Device Name : "Tape3"
    Passthru Name: "Tape3"
    Volume Header: ""
    Port: 3; Bus: 0; Target: 0; LUN: 0
    Inquiry : "HP Ultrium 6-SCSI 23DS"
    Vendor ID : "HP "
    Product ID : "Ultrium 6-SCSI "
    Product Rev: "23DS"
    Serial Number: "HUxxxxxxx"
    WWN : ""
    WWN Id Type : 0
    Device Identifier: ""
    Device Type : SDT_TAPE
    NetBackup Drive Type: 16
    Removable : Yes
    Device Supports: SCSI-6
    Flags : 0x0
    Reason: 0x0

  • H_Sharma's avatar
    H_Sharma
    Level 6
    10 years ago

    Hello Experts,

    Coming to my second query 

    I had taken the backup of four mount points.

    /usr
    /opt
    /var
    /home

    Excluded /usr and still backups had taken 32 kilobyte data and all other rest mount points have got backed up.
    /opt had some 5 gb data.

    Now I exlcluded /opt and it got backed up with 32 kilobype.

    Dont understand what is happening here? Why it is taking backup when I have already excluded it and there is also no skipping in the job.

    I could see one more thing that /usr folder was never backed up in BAR gui. However exclude list is working but it should say something in job details.

  • H_Sharma's avatar
    H_Sharma
    Level 6
    10 years ago

    But why its not skipping anything in the logs and there is no information as well just 32 kb :(

     

     

  • H_Sharma's avatar
    H_Sharma
    Level 6
    10 years ago

    Hi Marianne,

    I found 2 drives.

     

    HP - Support with Windows / Linux

    1:- Ultrium 6250 LTO6 -
    Fibre Channel
    HP^^^^^^Ultrium^6-SCSI KMS, SResv, SPR, WORM

    2:- Ultrium 6650
    LTO6 - Fibre
    Channel
    HP^^^^^^Ultrium^6-SCSI KMS, SResv,
    SPR, WORM

    Page no. 188 in HCL.

    Is it what we are looking for?

    So what do you say is it supported?

  • Marianne's avatar
    Marianne
    Level 6
    10 years ago

    You said that /opt had some 5 gb data.

    What do you mean with ...why its not skipping anything ...? 
    It looks to me that EVERYTHING inside /opt is skipped.

    Because you have /opt in Backup Selection, it still needs to backup /opt (you told it to in the policy).

    So, NBU backs up the folder name (32 Kb) and nothing inside the folder.

    If you do not want to backup a folder or filesystem, why put it in Backup Selection in the first place?

  • H_Sharma's avatar
    H_Sharma
    Level 6
    10 years ago

    Ok got it... Every time it skips a directory it will create an empty directory 32kb. Because i have made the exclusion list.

    Actually i could not test it earlier yesterday i got the chance to test it. Thats why i put it in backup selection.