Command Queuing, Write Caching, Read Caching.

NF4 Driver options for (S)ATA channels.
Safe to use? Will they cause stability issues?
What happends if you turn command queuing on say a non NCQ (I would guess it means NCQ) device?
And are read/write caching anything like NCQ, as in, are they optional features for a drive to have?

Never have had control over things of this nature, and I hate system instability. So just need to make sure.

Thanks,
Devii

Not sure about the NF4 drivers...

But for the rest of it. If you turn on NCQ on the controller with a drive that doesn't support it, nothing will happen. Could just take the safe route and disable it though...

In the sense that they are "optional" features, I guess read/write cache are similar to NCQ. They are present on the drive, but can be disabled through feature settings. I'm not sure _why_ you would want to turn them off as cache greatly improves performance, but its possible.

Just so there isnt any confusion though, NCQ and read look-ahead/write cache are NOT similar in what they do.

Well the driver just says "Command Queuing" ... does this include like TCQ and other normal Queuing methods?

For some further explanation on Ember's (very good) points:

Read/Write caching methods are designed to improve localized performance, which is most of your desktop work.

NCQ is designed to improve random access (server and heavy multi tasking) performance. Such patterns are not seen in a typical desktop environment.

You want read and write caching on, and NCQ off. If you are using multiple disk intensive applications at a given time, and both of them access the same physical disk at the same time, you would want to turn NCQ on. Otherwise, the load is not random enough and NCQ's benefit not large enough, to offset the overhead of NCQ. In most single task desktop scenarios, the drive's caching strategy picks up requests faster than NCQ will.

However, there is one caveat to write caching, and that is if the disk is removable and you intend to use the removable capability. If that is the case, you must use the "safely remove hardware" icon to close all handles to the drive and flush cached writes from the buffer to the physical disks before removing the drive, or have write caching disabled to begin with on the disk. This is why write caching is disabled by default on removable USB/1394 disks - if a write is cached in the buffer and not yet written to disk when the disk is powered down, the data is lost. Corrupt files may result, although recovery journals on NTFS and native Linux volumes usually allow the file to be reverted to it's prewrite state.

Interesting, many thanks for the explantation.
I did toy with the settings some, and turning off the caching options was horrid x.x;