Turning off disk write cache

[wpshooter]

Is there any downside(s) to turning off the disk write cache (other than a performance hit in the disk write operations) ?

Thanks.

 

[NogginBoink]

No; just a perf hit in write performance.

Be aware that many IDE drives will not disable their internal caches no matter what commands you send them (so I'm told).

 

[xtknight]

Other than performance I don't think so. But what would you turn it off for?

 

[wpshooter]

I am told that you can potentially have less chance of problems if you have a premature shutdown and/or lockup.

 

[xtknight]

Hmm. Well I wouldn't worry about it unless you do experience crashes. Even then, that's probably one of the last things that could cause it. Have you been having blue screens of death lately?

 

[wpshooter]

No, just wanted to know if turning this off could stave off a problem in the future ?

Thanks.

 

[xtknight]

Oh, probably not. I have never heard of such a problem caused by this. If you have an nForce 4 board, don't install the custom software IDE drivers and that can definitely help prevent further issues which tons of users including me have had. If you do have any BSODs let us know and we can help you to determine the source.

 

[Matthias99]

Originally posted by: wpshooter
No, just wanted to know if turning this off could stave off a problem in the future ?

Thanks.

Theoretically, you are somewhat less likely to corrupt the filesystem if you crash hard or suffer a sudden poweroff while writing some critical piece of filesystem data.

In practice, most *really* critical filesystem operations bypass the system write cache (and some sort of journalling or backups on disk are used to protect you from dying in the middle of them), so where you generally really risk losing data is from the cache on the drive itself. Not all drives allow this cache to be disabled.

Generally speaking, there are better things to worry about, and it can hurt write performance quite a bit in some cases.

 

[JimPhelpsMI]

Hi, Way back when Delayed Write was invented there was a real danger of the machine getting turned off while Delayed Write was writing to the Drive. That is really not a problem today as Windoz will not shut down until everybody is done. It will speed your system up a bit to leave it on. Luck, Jim

 

[corkyg]

There are always exceptions to every rule. For removable drives, it is best to turn off Write Caching and opt for quick removal. This lets you pop flash media in and out of USB ports without regard to the icon in the tray.

And . . . some external removable drives will give you delayed write messages unless you turn W/C/ off.

 

[VirtualLarry]

Originally posted by: NogginBoink
No; just a perf hit in write performance.

Be aware that many IDE drives will not disable their internal caches no matter what commands you send them (so I'm told).

That doesn't make sense - IBM's "FeatureTool" utility has reporting for both IDE HD read-ahead and write caching, and capability to manipulate those settings persistently for some (IBM) drives.

I would think that any IDE HD that didn't do as it was told would be defective, or pre-dating the inclusion of control commands for those features.

 

[Jeff7181]

Originally posted by: wpshooter
No, just wanted to know if turning this off could stave off a problem in the future ?

Thanks.

A better method would be to spend $100 on a UPS that'll give you 5-10 minutes of battery time in the event of a power outage, which is more than enough time to save your junk and shut the computer down.

 

[VirtualLarry]

Originally posted by: JimPhelpsMI
Hi, Way back when Delayed Write was invented there was a real danger of the machine getting turned off while Delayed Write was writing to the Drive. That is really not a problem today as Windoz will not shut down until everybody is done. It will speed your system up a bit to leave it on. Luck, Jim

This was one of the problems with Windows 2000, and especially the IBM 75GXP drive. Firstly, Windows would cut power to the system (ATX soft-off) before the HD's write-cache had time to flush itself (causing "\WINDOWS\SYSTEM.ced" errors with the registry), and in the case of the 75GXP with buggy firmware, it would retract the heads to the center of the spindle, while the head was writing to the drive! It would nicely scribble on things like the system part of sectors on the drive, turning them bad, and causing future bad sectors and seek errors on the drive. IBM blamed the problem on MS, MS blamed IBM, well, that's old news today thankfully.

This is one of the reasons why I still configure Windows not to auto-power-off on shutdown, and force it to clean the pagefile before shutdown, to flush everything else out of the write cache.