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How to enable Drive Write Cache on E200?

Mike Dross
Occasional Advisor

How to enable Drive Write Cache on E200?

I have an E200 with the BBWC installed with SAS drives in a DL380 G5. The the hpacucli command I cannot enable the Drive Write Cache. Below are the relevant outputs from the commands. What am I missing? Why can't I enable the Drive Write Cache?

hpacucli ctrl all show config detail

Smart Array E200 in Slot 3
Bus Interface: PCI
Slot: 3
Serial Number: PA6C90L9SV912J
Cache Serial Number: P9A3A0B9SV92RZ
RAID 6 (ADG) Status: Disabled
Controller Status: OK
Chassis Slot:
Hardware Revision: Rev A
Firmware Version: 1.82
Rebuild Priority: Medium
Expand Priority: Medium
Surface Scan Delay: 15 sec
Cache Board Present: True
Cache Status: OK
Accelerator Ratio: 50% Read / 50% Write
Drive Write Cache: Disabled
Total Cache Size: 128 MB
Battery Pack Count: 1
Battery Status: OK
SATA NCQ Supported: False

Array: A
Interface Type: SAS
Unused Space: 0 MB
Status: OK

Logical Drive: 1
Size: 136.7 GB
Fault Tolerance: RAID 5
Heads: 255
Sectors Per Track: 32
Cylinders: 35124
Stripe Size: 64 KB
Status: OK
Array Accelerator: Enabled
Parity Initialization Status: Initialization Completed
Unique Identifier: 600508B100104C3953563931324A0002
Disk Name: /dev/cciss/c0d0
Mount Points: / 63.5 GB, /weather 58.4 GB, /var 9.8 GB, /tmp 1000 MB
Logical Drive Label: A038EA87PA6C90L9SV912J5D96

physicaldrive 1I:1:1
Port: 1I
Box: 1
Bay: 1
Status: OK
Drive Type: Data Drive
Interface Type: SAS
Size: 72 GB
Rotational Speed: 10000
Firmware Revision: HPDC
Serial Number: 3NP28YN500009819BHZZ
Model: HP DG072ABAB3
PHY Count: 1
PHY Transfer Rate: 3.0GBPS
physicaldrive 1I:1:2
Port: 1I
Box: 1
Bay: 2
Status: OK
Drive Type: Data Drive
Interface Type: SAS
Size: 72 GB
Rotational Speed: 10000
Firmware Revision: HPDC
Serial Number: 3NP27F8700009818L36S
Model: HP DG072ABAB3
PHY Count: 1
PHY Transfer Rate: 3.0GBPS
physicaldrive 1I:1:3
Port: 1I
Box: 1
Bay: 3
Status: OK
Drive Type: Data Drive
Interface Type: SAS
Size: 72 GB
Rotational Speed: 10000
Firmware Revision: HPDC
Serial Number: 3NP28ZKS00009819VEGP
Model: HP DG072ABAB3
PHY Count: 1
PHY Transfer Rate: 3.0GBPS

Array: B
Interface Type: SAS
Unused Space: 0 MB
Status: OK

Logical Drive: 2
Size: 136.7 GB
Fault Tolerance: RAID 0
Heads: 255
Sectors Per Track: 32
Cylinders: 35132
Stripe Size: 128 KB
Status: OK
Array Accelerator: Enabled
Unique Identifier: 600508B100104C3953563931324A0003
Disk Name: /dev/cciss/c0d1
Mount Points: None
Logical Drive Label: A0269805PA6C90L9SV912JE5B6

physicaldrive 1I:1:4
Port: 1I
Box: 1
Bay: 4
Status: OK
Drive Type: Data Drive
Interface Type: SAS
Size: 146 GB
Rotational Speed: 10000
Firmware Revision: 0002
Serial Number: 3NM4GNXW00009829JEAG
Model: SEAGATE ST9146802SS
PHY Count: 2
PHY Transfer Rate: 3.0GBPS, Unknown

[root@lightning ~]#

~]# hpacucli ctrl all modify dwc=enable

Warning: Without the proper safety precautions, use of write cache on physical
drives could cause data loss in the event of power failure. To ensure
data is properly protected, use redundant power supplies and
Uninterruptible Power Supplies. Also, if you have multiple storage
enclosures, all data should be mirrored across them. Use of this
feature is not recommended unless these precautions are followed.
Continue? (y/n) y


Error: This operation is not supported with the current configuration. Use the
"show" command on devices to show additional details about the
configuration.

[root@lightning ~]#


6 REPLIES
Víctor Cespón
Honored Contributor

Re: How to enable Drive Write Cache on E200?

Mike, you have the answer on your own message:

Warning: Without the proper safety precautions, use of write cache on physical
drives could cause data loss in the event of power failure.

Accelerator Ratio: 50% Read / 50% Write

You have cache on the RAM on the controller, which has a battery, why do you want another write cache on the disks? It's unsafe, as they do not have a battery to keep the data if a power failure happens.
Mike Dross
Occasional Advisor

Re: How to enable Drive Write Cache on E200?

It is a feature that is supposed to work on the controller with the current version of firmware. It works on my P400 controllers and I have seen examples where others have used it on the E200.

Drive cache speeds up the hard drive access by cache stored sector maps.
Víctor Cespón
Honored Contributor

Re: How to enable Drive Write Cache on E200?

If you have understood that, since you have firmware 1.82 on the E200, you should be able to enable DWC:

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c01149818

Mike Dross
Occasional Advisor

Re: How to enable Drive Write Cache on E200?

Yes, there in lies the issue. It should be able to activate the DWC, but for some reason t will not despite the fact it has a BBWC and I upgraded the firmware. :-(
Greybeard
Esteemed Contributor

Re: How to enable Drive Write Cache on E200?

It seems to me you have the read and write battery backed cache on the controller running, %50/%50. the error message is refering to the Physical disk, which also has a cache buffer on it for when it is used without an array controller, this cache is not battery protected as it is on the hard disk's pcb well down the i/o line from the array controller.
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Manuel Malhado
Occasional Visitor

Re: How to enable Drive Write Cache on E200?

I had this same is issue in a DL180 G5 server with the same E200 controller, I was able to enable drive write cache by changing the hpacucli command from the one above:

ctrl all modify dwc=enable

to:

ctrl slot=0 modify dwc=enable (or maybe slot=3 for your particular case)