I recently built a new UnRaid server and just finished loading all of my data onto it - currently about 13TB worth.  It is almost all HD movies in .ts, .mkv, and .iso formats.  I am primarily streaming these movies to an HDI Dune 3.0 media player via SMB share over gigabit wired.

 

The other night I noticed a number of video related artifacts (blocking mostly, some skipped frames too) on a movie.  I tried another movie and the same problem.

 

I tried playing the same movie on my PC and noticed the artifacts there as well.  They didn't seem to be in the same places, though.  My first suspicion was a networking problem so I swapped out network cables and network switch - still same issue.

 

My next suspicion was bad memory on the UnRaid server so I ran a memtest.  I let it run for a couple of hours (I know - not a very thorough test) and it reported no errors.

 

Today I downloaded and installed md5deep on the UnRaid server to try computing checksums of some files and found something I didn't expect - running back-to-back md5 on the same file on the UnRaid server returns different results!

 

It doesn't seem to be just files on a single hard drive that are affected - it seems to be all of them.

 

Any suggestions on what else to try or how to diagnose further?  Here is a quick rundown of my hardware:

 

• ASUS M4A785-M Motherboard
  
• AMD Sempron 145 Sargas 2.8GHz Socket AM3 45W Single-Core Desktop Processor
  
• SUPERMICRO AOC-SASLP-MV8 PCI Express x4 Low Profile SAS SAS RAID Controller (6 drives plugged into motherboard - 7 more plugged into this card)
  
• SuperMicro CSE-933T-R760B 3U Chassis (15 SATA drive bays)
  

 

I have no cache drive and a single parity drive configured.

 

Thanks very much in advance!

 

-David

In the past, when it is reported it has frequently been the LAN chipset.  There were a few nforce4 chipsets that did the same, and at least one or two disk drives where repeated md5 checks  reported different results.

 

You can try running the same repeated md5 checks from on the server itself by typing:

 

md5sum "/mnt/disk1/path_to_your_file"

using, of course, the correct disk number and file name.

 

(oops, i see you did run the tests on the unRAID server with md5deep... that eliminates it from being the LAN)

 

Since you have 13 drives, is it possible you are stressing the power supply beyond its limits?

 

Memory is still the most likely suspect.  If you have multiple strips, try running with just one, and then with just the other. Odds of both being defective is very slim.  Also make sure the voltage, timing, and clock speed is set for your specific RAM.  Some BIOS get it right, some do not.  Many motherboards are very picky.

 

Do the bad checksums occur on both disk controllers? Perhaps it is only on the added card, or only on the motherboard.  Since all your hardware is new... all you can do is test by process of elimination.  Odds are very high the files on the disks are fine... now you just need to read them consistently.

 

Joe L.

Post the Unraid version you are using.

 

Post a syslog.

 

If possible run a test on each individual HD as I believe you are using these second hand cases and it may have some problems with a backplane

 

 

Thanks for the tips, guys.  When I got home tonight I pulled the two sticks of RAM out and popped in a different 1GB stick and guess what - my problem is GONE.  It is definitely some issue with the RAM (either bad RAM or misconfigured in BIOS).

 

My gut feel has always been that UnRaid does not have very intense memory requirements.  Is there any reason I would want to add a second stick (I believe most motherboards can improve memory access in some way when memory is added in pairs)?  Or is there no real benefit when it comes to UnRaid?  I'm inclined to leave well enough alone and stop futzing with the server if possible.

 

Thanks again for all your help.

 

-David

My gut feel has always been that UnRaid does not have very intense memory requirements.

Good idea

 

Is there any reason I would want to add a second stick (I believe most motherboards can improve memory access in some way when memory is added in pairs)?

Dual channel can speed up memory access

 

Or is there no real benefit when it comes to UnRaid?

For unRAID there is very little benefit to dual channel (i.e. non that you should notice with stock unRIAD)

 

I'm inclined to leave well enough alone and stop futzing with the server if possible.

Best idea at this point.  If it aint broken (anymore) don't fix it!!