Backup Exec "Compression Ratio"

[OGS]

After a backup job completes, under "Job Monitor" the job is shown as having 543GB of data on the tape. (LTO3)
Under the "Media" tab however, the tape is shown as having 206GB of data. I'm ok with that, but the Compression Ratio is showan as 1.03:1 -- that doesn't make much sense to me...

[Lou_Buffetta]

It depends on what make and model of tape library/drive you have. Backup Exec does not support Capacity and Compression on some models (e.g. EXABYTE VXA 1x10  1U).

Generate a BEDIAG report in Backup Exec then copy and paste the "Device Discovery" section into a post so I can take a look. Here are the steps:

 -- In Backup Exec go to the TOOLS menu
 -- Select the second item down "Backup Exec Diagnostics..."
 -- Click "Run Diagnostics" from the pop open window
   -- Make sure you are diagnosing the proper media server
      if Backup Exec is installed on multiple servers listed
 -- When finished a Notepad window will open

 -- Do a Find for "end adamm"

 -- Scroll back up to the beginning of the "Device Discovery" section

 -- I'm interested in the following information from both the tape and medium changer entries

    -- Device Name

    -- Primary Inquiry

    -- Secondary Inquiry 

Once I have this data I can make a better determination about your compression reporting.

[OGS]

I should also mention due to tape encryption,we are using software compression.

[2536] 07/12/07 14:28:02.687 Device Discovery:

Scsi Address
Prt :Bus :Tar :Lun   Attributes
-------------------  -------------------------------------------------------------------------------

0005:0000:0002:0000  Device Name             "\\.\MediumChanger0"
                    Secondary Name          "\\.\Changer0"
                    Primary Inquiry         "DELL    PV-132T         310D"
                    Secondary Inquiry       "DELL    PV-132T         310D"
                    Serial Number           "DELL    PV-132T         DELL1_313465BQ1765"
                    Device Flags            KSCSI, SN(TYPE 0), SN(ELEMENT)
                    Device State            3, Online

                    Device IDs              1002, {851C8A6C-9A65-4A93-ADE2-2423F8CB54F9}
                    Device Name             "DELL 1"
                    Device Type             2131755008, "CHANGER FS=1"
                    Device Features         0x00077E7F: EMBI,EMBM,IBE,INSMC,MPTP,MDTD,MSTS,PP,PES,PT,PMA,RMP,RRD,SMCAE,SMCE,TEI
                    1st Slot Number         1
                    Number Of Slots         23
                    Portal Slots            1
                    Import/Export           Robotic

                    Drive Element 0         1004, "1210063759"
                    Drive Element 1         1003, "1210062945"

0005:0000:0003:0000  Device Name             "\\.\Tape0"
                    Secondary Name          "\\?\scsi#sequential&ven_ibm&prod_ultrium-td3&rev_6b20#4&26e3ba9&0&030#{53f5630b-b6bf-11d0-94f2-00a0c91efb8b}"
                    Primary Inquiry         "IBM     ULTRIUM-TD3     6B20"
                    Serial Number           "IBM     ULTRIUM-TD3     1210063759"
                    Device Flags            KSCSI, SN(TYPE 1)
                    Device State            3, Online

                    Device IDs              1004, {C037214C-0512-4449-8448-2A337527DBF7}
                    Device Name             "IBM 2"
                    Device Type             134283265, "LTO 64K (64K,10,0,E,HU)"
                    Device Features         0x001BFA7F: PB,SFB,SRB,WFM,SFF,SRM,PEOD,EL,LU,E,SBS,DC,SDC,TA,HU,RR,W
                    Device Element          1002, 0

0005:0000:0004:0000  Device Name             "\\.\Tape1"
                    Secondary Name          "\\?\scsi#sequential&ven_ibm&prod_ultrium-td3&rev_6b20#4&26e3ba9&0&040#{53f5630b-b6bf-11d0-94f2-00a0c91efb8b}"
                    Primary Inquiry         "IBM     ULTRIUM-TD3     6B20"
                    Serial Number           "IBM     ULTRIUM-TD3     1210062945"
                    Device Flags            KSCSI, SN(TYPE 1)
                    Device State            3, Online

                    Device IDs              1003, {3734F041-6080-4EEA-BCE2-38258D677D12}
                    Device Name             "IBM 1"
                    Device Type             134283265, "LTO 64K (64K,10,0,E,HU)"
                    Device Features         0x001BFA7F: PB,SFB,SRB,WFM,SFF,SRM,PEOD,EL,LU,E,SBS,DC,SDC,TA,HU,RR,W
                    Device Element          1002, 1

-------------------  -------------------------------------------------------------------------------

[2536] 07/12/07 14:28:03.078 Start Rsm Support:

[2536] 07/12/07 14:28:03.093 Device Discovery End:




******** END adamm.log file ********

[Lou_Buffetta]

Thanks for the quick response -

Your tape library is well supported in Backup Exec.

In the job log you can check that data is being compressed by comparing the Backup Summary section to the Verify Summary section

  -- Actual byte count without compression is listed under "Backup Set Summary"

  -- Byte count with compression is listed under "Verify Set Summary"

There are 2 TechNote links below that you may want to consult regarding compression. I have been advising support customers not to use Software Compression at all with version 11d. The only setting you should use is "Hardware [if available, otherwise none]" - this will keep you out of trouble later should you need to restore something.

 Compression Ratio does not display or displays incorrectly when using software compression.

http://seer.entsupport.symantec.com/docs/273089.htm

Software compression does not work on Windows 2003 x64 or Windows XP x64 bit systems.

http://seer.entsupport.symantec.com/docs/287306.htm

[ELambee]

Hi,

Well, according to your admin guide (P. 409), you recommends to use SOFTWARE compression with encryption...

It all makes sense too. The hardware compression is being made after the encryption. The encryption process randomize data, so there will be no gain to use compression after that...

Can you confirm that its ok....?

Thanks

Message Edited by ELambee on 08-02-200706:48 AM

[OGS]

yeah, if you need to use compression and encryption - software is your only option. That being said, I personnally do not like the idea of being 'restricted' with by restore options later. Veritas, will be your only choice to undo the software compression.

[ChristianM]

I think it may also be true that if you are using encryption then Backup Exec will be your only choice to restore -  so using software compression adds no further restoration restrictions. 

[ELambee]

Yeah, you're right.

Also, I wanted to know how the software compression works.

As I can see, it looks like the remote server where I have the agent installed and from whom I'm doing the backup does all the compression BEFORE sending it to my BE server over the network...

I'm backuping a 54GB BD and it takes about 30 mins to copy to my BE server (100Mb/s connection). The size after compression is about 12GB... So, it makes sense that the compression occurs on the Agent server then its sent over the network to my BE server...Its impossible to copy 54GB over a 100Mb/s connection within 30 mins...At full speed (12.5MB/sec or 100Mb/sec), we are able to copy 45GB...

I'm I right?

Thanks

[OGS]

very good point !