Blackmagic Software
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Blackmagic Disk Speed Test
If you want to check your disk array speed, Blackmagic Disk Speed Test can be run to check the array
speed, and to provide the results in video frame rates. This makes it much easier to understand how
various disk arrays will handle video capture and playback at various video resolutions and frame rates.
Disk Speed Test provides more accurate results for large disk arrays, as often the manufacturer provided
speed results only check small data blocks, so you only get an indication of the cache speed of the disk
and not the sustained data rate of the disk. Video uses sustained data rates and only Disk Speed Test
provides a long burst of data for more accurate results.
Please see the seperate Disk Speed Test Manual for detailed information about using Blackmagic Disk
Speed Test. The manual is a PDF file and can be found on the installation CD or in the downloaded disk
image for your capture hardware.
Apple Xserve RAID disk arrays
The Apple Xserve RAID works great for both SD and HD when fully populated with 14 disks and at
least 512 MB of RAM for each RAID controller. We tested an Apple Xserve RAID
™
and for maximum
performance, stable capture and playback with uncompressed video we recommend the following
settings:
Check
Use Controller Write Cache
Uncheck Allow Host Cache Flushing
Check Use Drive Write Cache
Uncheck Use Steady Streaming Mode
Set “Read Prefetch” to 128 Stripes (8 MB/disk)
These are the settings we have found delivers stable capture and playback with uncompressed 10 and 8
bit video. However we have found uncompressed 10 bit 4:4:4 RGB is still not possible on a single Xserve
RAID. Other settings might also provide optimal performance and we recommend you check with your
local reseller before changing settings if you’re unsure of what these controls do.
Apple Xserve RAID preferences.
Blackmagic Disk Speed Test.
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