block size in NetWorker 7.2 under Windows 2000 Server

[marc0146]

Hi everybody,

I have a problem with NetWorker 7.2 block size, in fact, and the daemon log file, I have this message :

03/18/05 09:38:02 nsrd: media warning: \\.\Tape1 writing: unknown error 1117 (0x45d), at file 3 record 6950
03/18/05 09:38:02 nsrd: media notice: sdlt tape FULLSDLT.001 on \\.\Tape1 is full
03/18/05 09:38:02 nsrd: media notice: sdlt tape FULLSDLT.001 used 2986 MB of 273 GB capacity
03/18/05 09:39:02 nsrd: media notice: Volume "FULLSDLT.001" on device "\\.\Tape1": Block size is 32768 bytes not 131072 bytes. Verify the device configuration. Tape positioning by record is disabled.

Well, the problem is that a tape of approximatively 273GB is full WITH ONLY 2986 MB.

Also the \\.\Tape is a SDLT model; so according to the administration guide we create the environments variables such as:

NSR_DEV_BLOCK_SIZE_MSG=YES and NSR_DEV_BLOCK_SIZE_SDLT=256
(for the DLT7000, I know that the variable is NSR_DEV_BLOCK_SIZE_DLT7000 = value; but for the SDLT, the variable NSR_DEV_BLOCK_SIZE_SDLT is the good one ???)

Moreover, on the regedit tool, we create :

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aec67160\Parameters\Device41]
"MaximumSGList"=dword:00000041


We have used aec67160 because the SCSI card for the SDLT is an adaptec card called ACARD; on the card we see:ACARD ATP880-A MABA30701-C ACARD BIOS AEC67160 VER:1.10.2 LVD/SE 67160 REV:1.5

Finally the output of the commands scanner -vvv \\.\Tape1 and the mt -f \\.\Tape1 status give:

scanner: volume id 5047862 record size 262144

and

defaut blocksize = 65536
maximum blocksize = 1040384

If we change the tape by another one (a new one that never been used also) the problem is the same; the tape is never fill.

The tape is Quantum superDLT model.

Thanks for any advice,
Best regards,

Marc

 

[605]

I am pretty sure you have 3 problems:
- You simply have selected the wrong tape drive type in NetWorker
- You SCSI driver cuzs the block size after 64kB. This is a known problem and does not have anything to to with NetWorker at all. As it is a bit complicated to explain here, please read the "Performance Tuning Guide" for more details.
- Your tape could be bad and/or you are using the wrong device driver.
If NW can not recover, it marks the tape full and will not write to it any more


Do not forget that you have to make sure that the drive runs fine with the OS first. If this is not the case, do not blame NW as it will not use its own device drivers.

 

[marc0146]

Hi,

All the devices, also the SDLT, have the last drivers that the manufacters gave us for Windows 2000 Server.
The tape can not be bad because, we tried also new tape (10 new tapes); the result is the same (20 Gb can be backed up on a tape that can store 200 Gb; after the 20 Gb, the tape is marked full by NetWorker).

What do you mean by " the wrong tape drive " ? The tape is Quantum superDLT and is compatible for SDLT tape.(Before to be used, NetWorker label it normally).

Concerning the second point " This is a known problem "; which one it is ? (number problem, LGTxyz) Is there a special description that has been written for that ?

Moreover, the problem disappeared if we use an another product such as NetBackup ...

Now we will try some others tests but only with the SDLT that function, it means without the 2 drives such as DLT7000 (we will shutdown them).

Thanks,
Best regards,

Marc

 

[605]

It sounds that you do not like the answer. I try to explain, but i need an open mind.

First of all, i think NetBackup uses its own device drivers. If this is true, it is not the same with NetWorker - NW uses the device drivers from Windows, whether they are internal or external ones. As long as you do not test with another program (ntbackup??) which uses the same mechanism (drivers), you just compare pears with apples.

Your device drivers may be the latest, but they may be no good at all. That's why driver updates exist.

With respect to the problem of cutting the SCSI block size, this is known issue for years. Actually it is not a NW problem, it is as SCSI device driver problem which in general applies to all SCSI controllers. As it exists in general, there is a general solution. Once again, the info is in the "Performance Tuning Guide". If you don't want to read this chapter, it's not worth to talk about it.

If the tape is fine, then the problem is obviously related to something else - it can be one of the above. However, your argument that the tape is new, does not necessarily mean that it is good. There have been compatibility issues in the path with certain brands. Most likely no manufacturer will make these public. So this might also be the reason for a potential problem. As long as you have not successfully tested the media (with another software) completely you simply can not make a true compatibility statement.

Last, if you choose the wrong NetWorker device, the result can vary. First of all, the label is always written in 32kB blocks, on all NW devices. The further block size usually depends on the tape drive type. For SDLT it will be 128kB. However, if there is no "very special" (i can not be more precise) SCSI command used, you may even assign any tape drive with another (a wrong type). Most likely, it will not run optimally, but it will run.


I hope that this answer is a bit clearer now. Good luck.

 

[marc0146]

Yes it is more clearer for us.
We will see on the Performance guide if there is others things to do in order to increase the amount of datas on the tape.
I agree with you that probably NetBackup uses its own device drivers and NetWorker uses the device drivers from Windows; that's why we must try another product to see if there is difference.
Finally, we will see if we can improve the SCSI device driver by an update for example.
Well thank you 605 for all the informations,
Best regards,

Marc

 

[elgallo75]

Hi 605,
I am new to the forum but I am running the scanner command on a SDLT 320 tape drive at my DR site, trying to restore production data.

Im running into block size issues. (support is not gettin me anywhere) my production site is writing at 128KB.. and the SDLT drive at my DR is only seeing 32 for default and maximum size. How can I make my DR also support 128KB??
also where is this tuning guide you talk about? many thanks.

 

[marc0146]

Hi,

You will find the tuning guide on the following link:

http://web1.legato.com/infodev/publications/NetWorker/perftun/7.2/

We solve the problem by changing the SCSI card by another Adaptec card.

Best regards,
Marc

 

[605]

Have you selected the correct drive type? - the block size is automatically set with it. However, most SCSI drivers block after 64kB (SCSI, not FC) and you need to overcome this problem. More infos can also be found in the Performance Tuning Guide, perftune.pdf .

 

[Royster42]

Hi all,

Quick note on block size issues that we ran into recently that might well affect you. Since updating the driver for the Quantum SDLT 600/320's in the libraries we run on a couple of our sites we have had similar issues with Networker reporting an incorrect block size. We got this message when we attempted a restore from a ercently written tape. All our drives were set to use Default handler for its block size. Our server running Win2Kwas fine but our dedicated storage nodes running Win2003 had defaulted to 68kB from 128kB. The only way round this for us was to set the size as 128kB. As a result I am currently trying to find a good way of getting the data back off these tapes. Resetting the size back down does not work so I am off to play with scanner. Might have to use another library to get the info back :<

 

[605]

Also it is important to know that SP1 on Windows 2003 limits to block size to 64kB. You can not change this.

The only solution is to use the old tape.sys driver.