SCSI Hard Drive Write Cache

[MarksmanX 0]

Hi guys,

 

I just need some advice on SCSI Hard Drive Write Cache. Long time ago I had a SCSI Ultra 160 IBM drive that failed on me when I remember enabling Write Cache in Windows XP at RC1. When an error appeared in Windows XP it totally destroyed the SCSI Ultra 160 IBM drive. I couldn't boot from it and the Adaptec 29160 couldn't detect the drive anymore.

 

So I went into the Adaptec 29160 bios setting and enabled Write Cache when it was on N/C. Is this a good idea? Has this ever happen to any of you guys when a SCSI drive failed on your when you enabled write cache? It clearly states that if the drive fails or has an improper shutdown in XP it will most likely have a data loss or corruption on the drive if that occured. I don't know why it's enabled by DEFAULT! Any advice would help.

 

I didn't have Write Cache enabled on the Adaptec 29160 card when the Ultra 160 IBM drive got a fatal crash and destroyed that Hard Drive. I just enabled it recently and re-enabled the performance tab under harddrive. Thanks guys!

[EM 0]

I can't answer your question but I recently had a UW2 drive fail completely when I ran Norton Disk Doctor. Two drives in RAID and one failed. Sucks big time.

 

Write cache is enabled on mine and I cannot find where to disable it. Adaptec 131U Raid controller.

 

Ed

[MarksmanX 0]

From the adaptec site there is a bios update to version 4.20.26. Maybe once you update your card you can access that selected option in the Adaptec utility bios?

 

http://www.adaptec.com/worldwide/support/drivers_by_product.html?cat=/Product/AAA-131U2

[MarksmanX 0]

Ok I foundout it's not a good idea not to enable it if you don't have a UPS. This is from the Adaptec support site.

 

 

 

Quote:

What does enabling Write Back Cache do? What if the device does not support Write Back Caching?

 

This information applies to the following product(s):

 

- 19160, 29160N, 29160, 39160 - PCI SCSI Card(s)

 

This information applies to the following Operating System(s):

 

- All / PC

 

 

 

Answer

This feature overrides the SCSI devices built in Write Back Caching setting. If this switch is enabled, then the SCSI card will send a command to the device to enable write back caching (even if the default setting for the device is disabled).

If the device supports write back caching, then the command from the SCSI card will override any setting on the device itself. If the device does not support write back caching, then the it will ignore the command from the SCSI card. The default "No Change" (N/C) setting on the SCSI card allows the device to use its default setting for write back caching. Hard drives are the only devices on the market at this time that support write back caching - CDs, tape drives, removeable drives, and scanners do not support this feature.

 

Enabling write back caching increases performance (since writes are cached to cache RAM on the hard drive just like reads) but increases the risk of losing your data. Unwritten data in cache RAM is lost if and when the power goes out. This option should only be enabled if your system is protected by a UPS (Universal Power Supply) that will allow your system to go through a proper shut down sequence on the power of a battery even if the main power goes out. When the system properly shuts down the information from cache RAM is saved magnetically to the disk (and therefore is not reliant on power to retain the information). The risk of data loss is not worth the performance enhancement if your system is not protected by a UPS.