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I've got a HP ML350 G5 server running 6 disks as two RAID-5 configurations. This server has been notifying me of an empty battery on the E200i card. This seems to result in disabled cache: read and write speeds are very slow (around 20MB/s).

A possibility would be to replace the battery on the RAID card, but I don't really want to spend the money for the risk of losing data on power failure.

I found that it was possible to enable cache on the hard disks themselves, however, I can't find how this would be done on my server.

Another possibility would be to enable caching on the RAID card somehow, without replacing the battery.

Does anyone know how any of the above things are done?

Thanks in advance!

3 Answers 3

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The HP Smart Array E200i controller does not support the no-battery cache override option like newer HP controllers.

Replace the battery on the controller. You can leverage warranty (unlikely, due to the server's age), buy a part from eBay or another HP parts reseller. Don't buy new.

The ML350 G5 is an old system, mainly sold from 2005-2008. It's useful life is over, as it's been eclipsed by FIVE newer generations of HP hardware.

At this point, you should not have high expectations for the performance of the system. You can continue to run without controller battery, but DO NOT enable the individual disk caches. If the performance is unacceptable, buy the battery or plan to move to newer hardware.

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Does anyone know how any of the above things are done?

Please don't, when you sign up to this site it states pretty clearly that this site is for professional sysadmins - we do things professionally and the idea of enabling a hardware cache without some form of backup horrifies me and I'm sure many other SF members - so please don't. No idea where you are but if you let us know someone might be able to ship you a spare battery rather than watch you do this and then come back to us later asking for data-recovery services.

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  • In my case, I don't write to my server constantly/often, and most information I write to the server is still at another location on the occurrence of power failure. Losing the data in cache isn't such big problem in my case. I'm still considering to buy the battery, but I don't think the price is in proportion with what it does for me. I do get your point. However, although I'm not a professional sysadmin, I can image people do want a (temporarily) solution for this scene.
    – Tim N.
    Jun 10, 2015 at 17:10
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On some controllers there's an option to have a non-battery backed write cache, which you will be able to see by connecting to your RAID controller and seeing if it's an option. If it isn't an option for your controller, you may want to Google a bit and see if it's available in a later firmware version. Anything relating to the hard drives is irrelevant to what you're doing.

All of the above said, though, this is a terrible idea and you shouldn't enable a write cache without a battery behind it because it can lead to data loss.

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