Author: Val Language: text
Description: Followup from Episode 281 Timestamp: 2016-09-15 16:47:33 +0000
View raw paste Reply
  1. Hey TechSNAP team,
  2.  
  3. I just wanted to follow up on a previous issue I had submitted that you guys featured on Episode #281, specifically dealing with my issues with copying files between my ESXi hosted FreeBSD/Linux VMs and my FreeNAS mini over NFS shares.
  4.  
  5. Allan had recommended I mount my NFS shares via TCP, and possibly play around with rsize and wsize settings when mounting the shares. He also recommended I perform some tests using DD to test copying files from the NFS share, but write to /dev/null on the VM.
  6.  
  7. First thing I did was verify that NFS shares were already being mounted via TCP, as this appears to be the default setting when mounting NFS within FreeBSD and Linux. I skipped playing around with the rsize and wsize settings, as the FreeBSD "mount_nfs" man page states that these settings are specific to UDP mounted shares.
  8.  
  9. I then gave the DD command test a run, using a 3GB mkv file from the FreeNAS as the source file over to /dev/null on my Sonarr VM, and what do you know, the output stated I was transferring at 100MB/s! So that definitely rules out the FreeNAS or NFS being the culprit.
  10.  
  11. I then performed the exact same DD test, only this time my source file was the same 3GB mkv sitting locally on my VM's local disk. And lo and behold, DD states file transfer speeds of 30MB/s. Holy crap, only 30MB/s to a local disk?! What the hell is going on?
  12.  
  13. So fast forward a few days later, after research and pouring through various forum posts, I finally was able to narrow down the cause of my headaches. Back when I bought my VMware server, I had ordered an addon "Dell SAS 6/iR Adapter" RAID card and neglected to do any research on this specific card when running VMware ESXi. Turns out the RAID card is the non-battery variety, and as a consequence write-back cache is permanently disabled. Combine a non write-back cache RAID card with ESXi, and you're looking at miserable disk performance issues, as per the various forums validated in my search for answers.
  14.  
  15. So now I'm in the market for a PERC 6I with battery to replace my piece of crap RAID card, but at least now I know what's going on with my server issues.
  16.  
  17. I really want to thank you guys for finally helping me figure this extremely irritating issue out. Your show, and really the entire network, provide both entertaining and valuable information for us IT folk. Keep up the amazing work!
  18. Permission: I grant permission to read or post this feedback on-air and/or on the website.
View raw paste Reply