Write Cache on Raid 0

Ferret_Style · May 9, 2006, 05:55 AM

I notice you can turn on and off write caching on the drives in my raid array... what are the benifits of having it on or off?

PangingJr · May 9, 2006, 06:04 AM

Enable or Disable the Hard Drive Write Cache

Hard Drive Write Cache is a performance-enhancing feature supported by some hard drives. Enabling the write cache improves performance by temporarily storing data before it is written to the hard drive. The disadvantage of enabling the write cache is that the cached data may be lost if the system loses power.

Matth · May 9, 2006, 03:23 PM

Write cache - good for speed, bad for safety?

Actually, most drive write caching will only allocate a small part of the buffer, and will be forced to commit quite quickly - more a case of "posted write" than caching. There is a window during which writes may be incomplete and potential for a little more disruption than would otherwise be caused during a power failure or other improper shutdown.

Modern drives and controllers should handle caching safely under all normal conditions. There were some older examples where a normal shutdown sequence would not be guaranteed to write the cache, but that was a long time ago, though one reason for considerable mistrust of the write caching option.

May 9, 2006, 03:23 PM	#3
Matth Flash Banner Hater Join Date: Jun 2002 Location: UK Posts: 3,426 Rep Power: 93 System Specs	Write cache - good for speed, bad for safety? Actually, most drive write caching will only allocate a small part of the buffer, and will be forced to commit quite quickly - more a case of "posted write" than caching. There is a window during which writes may be incomplete and potential for a little more disruption than would otherwise be caused during a power failure or other improper shutdown. Modern drives and controllers should handle caching safely under all normal conditions. There were some older examples where a normal shutdown sequence would not be guaranteed to write the cache, but that was a long time ago, though one reason for considerable mistrust of the write caching option. __________________ Mary had a little lamb, Her father shot it dead Now Mary takes her lamb to school, Between two crusts of bread

May 9, 2006, 06:04 AM	#2
PangingJr Member Join Date: Mar 2003 Posts: 5,989 Rep Power: 71	Enable or Disable the Hard Drive Write Cache Hard Drive Write Cache is a performance-enhancing feature supported by some hard drives. Enabling the write cache improves performance by temporarily storing data before it is written to the hard drive. The disadvantage of enabling the write cache is that the cached data may be lost if the system loses power.