Drobo

Data Errors

Drobo & data corruption
I am noticing errors in files as I move data around as I consolidate and remove duplicates. I use a combination of MD5 Summer and Quickpar2 to verify a copy/delete (NOT a MOVE), and I am finding an average error rate of 1 error per 100 gigs. I have had both write and read errors. What are other people’s experiences and what can I do to shrink the error rate further. I think some of the problem is that I have a workstation and server as below…

Workstation
Win7x64 10/100 network card

Server
Win7x64 gigabit network card
6 drive, 1 TB each in an Adaptec Raid 6 controller.
Drobo A Hooked up via USB 2.0 - Unsorted files. Backup of Adaptec Raid
Drobo B Hooked up via USB 2.0 - Video DVD iso’s.

Transfer method - 350 Gigs

Using windows 7 drag and copy method, the date took the route of: Drobo A > Ram of Server > 1GNnic > 1Gig switch > 100 MB nic on motherboard of a Dell Vostro 200 (low end) > Ram of workstation > 100MBDell Nic > 1 gig switch > 1 Gig NIC > Server Ram > Drobo Drive B.

Verify method.

On the workstation run MD5 Summer to create the MD5 file from Drobo A.

copy the MD5 to the same relitive location on the Drobo B, and let it verify the files.
Found 3 errors,
“Movie 1.iso”
“Movie 2.iso”
“Movie 3.iso”

Using Quickpar, there were NO bad/corrupted blocks in “Movie 1.iso”

This seems to be a read error from Drobo B as a false positive error in the verification process.

Using Quickpar, I found 1 bad block in “Movie 2.iso” & 1 bad block in “Movie 3.iso”
This seems to be either a read error from Drobo A or a Write Error to Drobo B, or a corrupt packet when going back and forth across my home network.

What if anything, can I do to reduce/eliminate the errors that I am getting? The only odvious step is to to the copy/delete on the server to elimate the network errors.

On video ISO’s a single bad byte will not significatly affect me as it is only 1/30th of a second glitch, but the same error rate will apply to critical items like program, encrypted files and personal documents.

This is somewhat outsize the scope of the Drobo, but as storage of data has increased, the error rate seems to have stayed the same for the last 10 years or so.

MD5 will only detect errors, QuickPar2 does not work well on lots of small files scatted in many directories. I don’t want to rar everything as it makes using the data difficult.

http://www.quickpar.org.uk/
http://www.md5summer.org/