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We keep getting emails notifications as it switches between enable and disable. It is old hardware so we won't be replacing the batteries.

This is the alerts we are getting.

Accelerator Board Status Change: Slot 5.
Status is now Temporarily Disabled.
Accelerator Board Status Change: Slot 5.
Status is now Enabled.

Question. Can we disable the cache while the system is live? Which options in hpacucli do I need to change? Seems like there is quite a few.

<target> modify [arrayaccelerator=enable|disable]
 Enables or disables the array accelerator for a given logical drive. The
 target can be any valid logical drive target on a controller that supports
 array accelerator management.
<target> modify [drivewritecache=enable|disable|?] [forced]
 Enables or disables the physical drive write cache for the controller. The
 target can be any valid controller target that supports drive write cache.
<target> modify [nobatterywritecache=enable|disable|?]
 This option allows write caching to be enabled when a battery/capacitor is
 not present or fully charged. This setting affects all logical drives
 created on the controller and there must be at least one logical drive
 present before usage.
lbanz
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  • No offence, but do you understand the impact of those options? Turning off the write cache could seriously impact performance, and enabling the write cache without the battery could compromise your data integrity. You should be able to pick up some batteries for a few quid. – Dan Dec 11 '14 at 10:52
  • @Sven Yeah, I know what a BBU looks like. I'm seeing new ones for <$50 over here, but I guess that's variable and depends on your definition of cheap. If these servers are production, then paying $100 should be a no brainer. – Dan Dec 11 '14 at 11:05
  • @Dan Yes I'm aware. But at the moment it is flickering between the two as the battery is on it's last leg. Most of the time it is in disabled mode. I just want to to disable it completely so we don't get spam. – lbanz Dec 11 '14 at 11:06

2 Answers2

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If you REALLY want to do disable this Write Cache, then you need the second option. 

drivewritecache=disable

The first option merely stops a particular logical drive from utilising it. The third will allow the cache to function, but you'll lose the battery backup which is inherently dangerous.

Dan
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  • I was thinking I need to disable the 3rd one just in case it tries to enable cache without the battery present. – lbanz Dec 11 '14 at 11:11
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Buy new batteries... Buy used batteries... Call HP... If you're planning to continue running a server that old, at least do it well :)

Yes, you can disable the battery requirement for write cache... if you're not concerned about losing in-flight writes during a crash or power failure, that's fine. My bigger concern is that those old batteries will begin to swell. I've seen it happen, and it's a bit gross (one exploded inside of a DL180 G5 chassis).

See: Smart Array P400 - Accelerator Replacement Battery Failure

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ewwhite
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