Frame drops may occur during video editing.


Some common issues may effect the trasfer rate from the Promise EClass VTrak to the Fibre network.


Please review the following points of the Promise VTrak made for mac / XSan2 configuration:

  • Make sure all LD cache settings and controller settings are configured properly per the recommended Apple scripts. Please read the following: Configuring VTrak for optimal performance in an Apple/Mac environment 
  • Make sure there are no Background Activity (BGA) running on the VTrak.  
  • Make sure the battery is not marginal or under 72 hours hold time. Low battery hold times under 72 hours will disable LD Write Cache on the vtrak controller (this is a feature of Adaptive Write Cache) With the LD Write Cache disabled, frame drops will occur specifically during ingest/capture.
  • Use a dedicated Metadata controller and ensure the Metadata network not sharing with public network. Its also recommended to create a dedicated VLAN for the Promise MDD SAN.
  • If only one client is dropping check the Ethernet cable. Make sure both VTrak management ports are attached to an ethernet switch or hub. Having none, or only one management cable attached can effect the bandwidth.
  • Check the PCIe bus bandwidth. Card order and slot settings will be important. Please read the following: Configuring PCIe slots for best bandwidth 
  • Pay close attention to HD video format in question and the number of simultanious streams.  The more streams or the higher the resolution of the HD video, the larger the bandwidth requirement. Please see: Xsan 2 in video post-production
  • Verify the FC fabric settings and initiator settings. Type fc -v at the CLI or look under [FC port info] in the subsysteminfo log for the settings.
  • Carefully sift the logs and pay attention to events. Make sure any error counts are stagnent and not incrementing. Type fc -a list -t stats at the CLI, or look under [FC stats info] in the subsysteminfo log to view error counts.
  • Use a Fibre switch that can intercept the RSCNs on the network. See the QLogic Fibre Switch with IO Stream Guard
  • Get the following cfg logs from XSAN to confirm the Stripe Breath. This log is in: etc/Library/Filesystem/Xsan/configs (get all *.cfg files)
  • If you are experience frame drops in Vtrak EClass/JClass configurations during real time ingest and playback with applications such as Forks with Final Cut, you may want to try other “Stripe Breaths” We have seen better performance with using VTrak EClass/JClass configurations using 32 Stripe Breath for the XSAN video volume. It is recommended to always create XSAN storage pools in multiples of 4 LUNs for best performance.