We are using an embedded windows XP PC as a logging device in an environment where there is a risk of loss of power.
We have dual redundant drives to act as the logging target - one is the system hard drive and the other is a removable hard drive (using a USB to SATA CRU Dataport 25 caddy system)
Under test we've found that significant loss of data (up to 3 hours worth in terms of log time) occurs if the power is interrupted, and we're looking to try to reduce that by disabling all write caching that may be occuring.
We've looked at the disk device properties (Policies tab) and when logged in as an Adminstrator we see that the USB drive is set to "Optimize for quick removal" - which we'd expect to mean the removable drive looses less than the system drive which is set to "Optimize for performance" - however this doesn't seem to be the case.
Also suspiciously when logged in as a named user (the normal running configuration) without permission to change device settings the USB drives show "Optimize for performance" though it is greyed out - this may be an artefact of not having required permissions but it seems to contradict what is shown as an Admin.
What can we do to force windows not to cache writes to either disk?
What write caching if any may occur at the hardware level and do disks exist where this can be disabled?
Exact Part nos below:
- Seagate HDD (Part No. ST9320421AS)
- DP25, USB-SATA Dual Drive, (PartNo. 8570-3371-9500)
- DP25 Complete Assembly, Dual SATA Drive, (Part No. 8510-5002-9500)
- DataPort® 25 USB-to-Dual SATA HDD (Part No. 8512-3370-9500)
