eSATA and write caching

[disord3r]

A few weeks ago, I purchased an external eSATA drive and have been transferring a large amount of data to it, as it will now be my primary backup device. After having the drive for less then a day, I immediately started getting notifications in XP of "delayed write failed" after I have turned the drive off.

After some googling appears to have to do with write caching on the drive. Since the system recognizes them as internal disks and not removable storage, it's using write caching on them for a performance boost. I don't have the "safely remove" option for these drives, so the only way I can ensure that I'm not encountering data loss is to shut down the system before I shut off the external drive, forcing the cache to be written immediately. No biggie, lesson learned. I recreated all the data on the drive to ensure it was intact and went about my business.

Then I found out that I could selectively disable write caching for drives via the Policies tab of the properties of the specific drive in device manager. I thought this was the fix and that I no longer need to shut down my system to flush the cache, but I quickly found out that Windows re-enables write caching on the drive each time I reboot. I became aware of this when, after I thought I had disabled write caching, I began getting "delayed write failed" messages again... a FULL 7 HOURS after I shut off my external drive.

How delaying data writes for 7 hours is considered a performance increase is beyond me, but I'm more concerned with the fact that I can't keep the write cache disabled. I find myself having to toggle that option every time I use the external drive, and it's becoming a pain in my a** at this point.

Any ideas how to keep that disabled? Supposedly there is a dskcache.exe utility which would allow me to do this via command line (meaning I could script it on startup), but good luck finding it. The Microsoft support KB article entitled "Obtaining dskcache.exe ..." doesn't even link to it anymore. I also can't find any references to it in the registry.

Thanks in advance.

 

[kjv1611]

How important is performance with the eSata drive? If it's not THAT important, you could try changing it from "performance" to "easily removable" mode. You can do this with any hard drive, best I remember..

I can't remember off hand where to access that option, but I will try to find it later this evening or tomorrow if no one else has beaten me to it... or unless you're able to do it on your own..... OR unless you happen to find another solution before then.

If the drive is for back-up only, then this may be your best solution.

 

[disord3r]

While I did specifically get an eSATA drive for performance, it was only because I find USB to be painfully slow when moving the amounts of data I plan to move onto this drive. I'm certainly looking for the fastest thing I can get, but I'm willing to sacrifice a little if it allows me to maintain data integrity at the same time; fast does me no good if everything's corrupt.

I will mention that I'm using XP, and for some reason those mode names sound suspiciously like something you'd find in Vista or W7. In fact, they sound like the Vista/W7 equivalents of enabling or disabling write caching.

It's not that I can't find the option to do what I need - it's just that it doesn't "stick" when I reboot.

 

[kjv1611]

I'm pretty sure I've seen those in XP. I'll have to boot up an XP machine, and take a look later this afternoon.

I'm just on for a second right now..

 

[disord3r]

Well, you're right. I did manage to find them in XP on my work machine (Device Manager > HDD Properties > Policies tab). The single internal SATA HDD shows up with those options (which are actually grayed out for some reason). The text along with each of those radio buttons directly refers to write caching.

However, at home, the eSATA drive has different options on the Policies tab. It actually has a check box for enabling/disable write caching, along with some other radio button options which I can't remember. I'll see what they say when I go home for lunch.

Both computers in question are running XP Pro SP3. It could be that the dialog is slightly different between your boot drive and any other drives you might have.

 

[kjv1611]

Yeah, it probably would be disabled for the boot drive, system drive, as changing that could really make things go haywire, I'd imagine.

Also, if there are differences between home and work, that COULD be if you have XP Home at work, but XP Pro at work. And if that isn't why, it could be a policy or script set at work which you obviously wouldn't have at home either.