Data Corruption

Hi,

I just realised that data get corrupted when I copy files from MS Vista to to my N5200 PRO.

I noticed that my videos had occasional block errors when playing from the N5200. Did not think this was an issue with the N5200, as I thought my source also had the problem.

Recently I noticed that my source did not have this issue. I investigated, and found that every copy operation created random corrupted 2 byte (word), for every approx. 50 - 100 MB in a 700 MB file.

I have copied the same file many times, and the errors happen every time, but at different places in the file.

I have validated that this is not an issue with my operating system, or LAN by copying between two computers on my LAN.

All my 5TB of data might be corrupt !

Does anybody else have this expierence with the N5200, or is it just me ?.

Regards Lars

Lars,

I just checked with my box (FW 2.00.00.11) and a computer running XP using a 1 GB test file with a well known pattern. With my setup I was not able to reproduce this:

(1) file created on the NAS
(2) file copied over to the XP box
(3) file copied back to the NAS with a different name
(4) compared both files (cmp)

/Falk

Dear Sir,

If N5200 RAID status is health, please try the File System Check to correct the file system via V2.00.03 or V2.00.04 in this week.

Thecus Support Center

Yvon.

Hi,

Thanks for your response.

I am using FW version 2.00.03, is this a known error ?

Is the filecheck feature working correctly with this FW version ?

It definitely do not seem like a file system issue, more like a buffer overflow issue in the kernel, as only set of two bytes (word) are corrupted, every 50MB-100MB into the file.

Also, I can correct the file on the NAS, by doing a hex compare and writing/copying the currupted bytes a second time.

Also, I found on the internet, that Linux had a problem like this, very hard to track, in december 2006. Maybe this is related - if you / Thecus has based the NAS N5200 upon am early 2006 version of linux.

Regards Lars

Hi,

I found that the problem is only associated with writes, not reads.

and, by disabling the "File Access Cache" under "SMB/CIFS", the problem seems to disapear.

Need to do some more testing.

Regards Lars

Dear Sir,

1. On thoery File Access Cache won't related to this issue, thus we would recommend run the file system check better.

2. Also we could run the file system check vi V2.00.04:
http://www.thecus.com/Downloads/N520...FW_2.00.04.bin


Yvon.

Hi,

I have now upgrated to 2.00.04 and run the file check - no errors found.

I still see occational file corruption (2 bytes) when writing to the NAS from Vista.

The occurances are random. Sometimes no errors in a copy, sometimes 10 x 2 bytes spread over the entired file being copied. Seen in large files - 500 MB to 2 GB

The occurances seems less frequent that with 2.00.03.

I can correct the error by patching the individual corrupted bytes manually

No errors occur when reading from the NAS.

Any suggestions Yvon?

Regars

Dear Sir,

How about the file access cache is disabled? this function would enchance reading peformance for mas small size file.
Have we try on others PC as like Vista or FTP?

Yvon.

Yvon,

file access cache is still disabled.

I will give it a try from my other PC's and using FTP.

I will try with and without file access cache.

Regards Lars

Yvon,

I found the error !

The corruption had nothing to do with the N5200, it came from the Realtek Giga LAN driver installed on my Vista PC - Driver was from Jan 2007. Updating to the latest Realtek driver from December 2007 solved the issue.

Now I "just" have to fix the corrupted files

Thanks

Lars

Dear Sir,

Thanks for your informaiton about this issue, we will add to our FAQ base sharing with other users.

Yvon.