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Data error (cyclic redundancy check).

Mark Maiden
Occasional Advisor

Data error (cyclic redundancy check).

I have not been able to find a good source of information for fault finding this issue and I was wondering if someone could please help?

Server Windows 2000 SP4 on DL380 G3 with a Smart Array 5i SCSI controller.
Backup unit is a SDLT 160/320 with firmware rev 75. Not sure which SDLT drivers to use Quantum, HP or Veritas, but currently using the Native Quantum drivers?
Backup software is Veritas Backup Exec 9.0 or 9.1 (I say this as this issue is on several servers that have similar problems)
Tape Media we use currently are using is Imation?

Any suggestions will be gratefully received
8 REPLIES
Claudio Ruzza_1
Valued Contributor

Re: Data error (cyclic redundancy check).

Disable Removable Storage service in Win2K, unless you already did it.

Upgrade your drives' firmware to Ver. 82

Are your SDLT drives connected to the smartarray board?? If so, you are in a problematic configuration. Tape and disk drives should be conneted to different SCSI buses.

Check you are using the latest HP driver for your SCSI card also.

Hope this helps
Claudio
Mark Maiden
Occasional Advisor

Re: Data error (cyclic redundancy check).

Claudio thank you â I shall investigate/try your suggestions and get back to the forum
Further to this issue it does not happen on a regular occasion. We have 15 servers of very similar configurations and this issue only really happens to about half of them and on average there would be about 15 to 20 errors of this type across these servers.
The â Removable Storageâ service was not disabled
Shall look at updating the SDLT firmware.
SDLT drives are connected to the same Smart Array controller (5i) as this is a standard configuration from HP â same SCSI card, but the SDLT is connected to the external port and the disks are connected via the internal port? I am curious about your reasoning to change this? Are they not on different BUSs?
The SCSI drivers were one revision behind â 5.46.2.3
Claudio Ruzza_1
Valued Contributor

Re: Data error (cyclic redundancy check).

Mark,
I apologize, I wrongly did assume you were connecting your disks and tapes on the same BUS.
However, I've never seen before a server in which the external BUS of a SmartArray was used to manage a tape drive or a library, despite is supported. I believe is for two simple reasons: performance and reliability of your server. Performance, because the Smartarray dual BUS sits on the same PCI slot of your server; Reliability, because if your tape for any reason comprmise the SmartArray functionality you may see your disks disappear....
Bye Claudio
Leslie Martin
Frequent Advisor

Re: Data error (cyclic redundancy check).

External tape Drives are supported on the 5i Controller. In my experience CRC errors are usually associated with either bad media or a faulty tape drive. Try using brand new media after running a cleaning tape through the drive. If the problem persists its probably a faulty drive
Stuart Whitby
Trusted Contributor

Re: Data error (cyclic redundancy check).

The general reason for not connecting tape drives and disks on the same controller is that the different blocksize causes hell for all involved, and performance drops significantly - especially if doing local disk-tape backup. I'm not sure about the card in use here. If this is a dual controller card, then you will probably be okay. If it's a single SCSI bus, then you're mixing them.

There's another good reason to avoid these in cluster configurations. SCSI bus resets are sent to the disks as part of the cluster control. Sending this to a tape drive is bad news - if it's a single spindle drive it will be rewound. If it's in the middle of writing, it will get an I/O error and probably get marked suspect/poor/ugly, kicked out of the drive, and you lose its remaining capacity.

The other reason I've seen for CRC errors in the past is simply that the last block was not written fully to tape. NetWorker used to throw out these errors a few years back most times it hit the end of tape, since the data was verifiably incorrect for that block. It wasn't a problem, since the block got written correctly at the start of the next tape, but check that this isn't at the physical end of the media - might be something similar coming up in your environment. Just go to end of tape on a tape that gave this error and write an MB or so - if the write is successful, you hit this before the end. Being at the end of tape when you do this shouldn't cause any problem for recoveries through Backup Exec - its data is still there.
A sysadmin should never cross his fingers in the hope commands will work. Makes for a lot of mistakes while typing.
Chris Turnbull
Valued Contributor

Re: Data error (cyclic redundancy check).

OK, we use a lot of this sort of setup with minimal problems.
1) We use the Veritas drivers for the drive (as we are using the Veritas backup software).
2) We use (generally) Quantum media, also Maxell from time-to-time. Just personal, but I don't rate Imation media.
3) Cleaning tapes are run weekly as a rule, tapes replaced after the manufacturer's recommended usage.
4) Don't use media across different drives - each unit tends to have it's own 'personality' to do with the slight differences in calibration.
5) If you get a CRC error more than once with the same tape - bin it.
Mark Maiden
Occasional Advisor

Re: Data error (cyclic redundancy check).

Thank you one and all for all your help and advice.
I managed to upgrade firmware to version 82, not apparent issues. Upgrade the Veritas drivers for the SDLT 160/320 to version 5.0.1.1 (date 11/02/2004). Apply HP Proliant Support Pack 7.10 which also included the driver for the SCSI Smart Array 5i card, driver version 5.60.0.32 (21/01/2004).
With all done the error continued â swapped SDLT drive and all is now okay.

Stuart, Claudio and Leslie I am most grateful for your assistance. Generally I have followed these standards, but your advice has supported it a lot more.
Chris, I also thank you for your advice as that is generally what we do, although we do use Imation media â might have to speak to the procurement team! I am afraid that I have not managed to find much information about media and which one to use? I suspect it becomes a personal choice?

Regards
Mark Maiden
Occasional Advisor

Re: Data error (cyclic redundancy check).

Please see my previous comments.

Thank you once again.

(New to this forum which was most helpful)