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Write Cache - SCSI Drive

Occasional Advisor

Write Cache - SCSI Drive

On Win2k Server with SmartArray 6i controller, Firmware Version 2.84, with Battery Backed Cache - and the controller stating - Cache Enabled.

In Device Manager > Disk Drives > HP Logical Volume SCSI Disk Device | Properties > Disk Properties. Write cache enabled is deselected. Upon selecting the option either a reboot or re-opening the property page, the option does not stick, it reverts back to deselected.

This is NOT the case on another server with the same controller/driver and firmware version, the Write Cache Enabled is selected.

Both servers are running the same drivers:
Hard drives - MS 5.0.2183.1 11/14/1999
SCSI controller - HP

An MS utility Dskcache.exe confirms that the disks do not have write cache enabled.

The only different item I see is when running a 3rd party IO tool (SQLsim), it reports two different "Storage manger name" values. The server that does not allow for write cache to be enabled states FTDisk and the server that does have write cache enabled has PhysDisk shown for this value.

HP support stated that the controller shows cache is enabled and punted to Microsoft, which of course I can't call because this is Windows 2000 - out of support.

How can I enable Write Cache on the drives?



P.S. This thread has been moved from Disk to ProLiant Servers (ML,DL,SL). -HP Forum Moderator

Honored Contributor

Re: Write Cache - SCSI Drive

Let's make one thing clear here. The disks that thw window OS sees are not physical disks they are the logical devices that the 6i controller presents to the OS. So write cache for a logical device does not apply.

I don't know why on the other server the write cache is enabled as you say. Can you confirm that the write cache is enabled for a logical device on the other server?
Respected Contributor

Re: Write Cache - SCSI Drive

You don't want to enable the write cache on the individual harddrives. Using this can lead to data loss in case of a power failure.
You should only enable write cache on the BBWC module (Not possible if the battery has a failed status).
If the write cache has been enabled on that other server I would make sure I would disable it a.s.a.p.
Occasional Advisor

Re: Write Cache - SCSI Drive


Ok, I'll go with... don't worry about Write Cache! Thanks.

But, yes, the other server a fresh install of Win2k > Sp4, using SmartStart CD had the Write Cache Enabled by default. See attached.

Do you guys recall any documentation that speaks to this? I've seen the documentation from MS stating to NOT turn on Write Cache unless there is a Battery - which there is, on the RAID controller.
Honored Contributor

Re: Write Cache - SCSI Drive

You should perform a check on the raid controllers and ensure that the cache settings are good. Verify that there are no cache memory failures and no battery failures. If the battery fails or does not charge, the controller will disable the write cache.
Occasional Advisor

Re: Write Cache - SCSI Drive

From the Array Diagnostic Utility for the server that Write Cache is not able to be applied to the Logical Drive in Device Manager, most looks OK except for a not at the end.

I'm clear on the Write Cache option in the GUI not necessary / shouldn't be set BUT why it was set automatically and is not able to be set on another is not clear.

How can I validate that that my settings are optimal?


Image Revision: 2.84
Recovery ROM Active Image
Flags Status: 0x01
Percent Write Cache: 50
Daughterboard Size(MB): 128
Cache Battery Count: 1
Total Ctlr Memory Size: 192
More Controller Flags: 0x18
X-Board Host I2C Autorev: 0x00
Battery PIC Rev: 0x20
Logical Drive 1:
Logical Drive 2:
Logical Drive 3:
Array Accelerator is enabled for this logical drive.

Logical Drive Disable Map: 0xfffffff8
Read Cache Size: 64 MBytes
Posted Write Size: 64 MBytes
Disable Flag: 0x00
Status: 0x00000001
Disable Code: 0x0000
Total Memory Size: 192 MBytes
Battery Count: 1
Battery Status: 0x0001
Parity Read Errors: 0000
Parity Write Errors: 0000
Error Log: N/A
Failed Batteries: 0x0000
Board Present: Yes
Accelerator Failure Map: 0x00000000
Max Error Log Entries: 16
NVRAM Load Status: 0x00
Memory Size Shift Factor: 0x0a
Non Battery Backed Memory: 0 MBytes
Memory State: 0x00

Of note is: For the "Phys Drive Flags:" value I get "Drive write cache setting is changeable and safe" for all but one drive.