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Enabling RAID5 on DL365 G5 Entry Model (411358-001)

epretorious
Regular Advisor

Enabling RAID5 on DL365 G5 Entry Model (411358-001)

I've just recently purchased a batch of DL365 G5 Entry Model servers (411358-001) and need to upgrade the E200i controller to enable RAID5. I've read the Quickspec for the DL365 G5 and it specifies the 128 MB Battery-Backed Write Cache with Battery Housing (HP P/N 346914-B21). When I look for information about the 128 MB BBWC (e.g., eBay), however, it gets confusing: Some information indicates that this item is a PCIe card and other information seems to indicate that the item is a mezzanine card (with attachments) and most sources imply that HP P/N 346914-B21 is for the HP SmartArray 6i and make no reference to the E200 or the E200i.

 

What is the correct part to enable RAID5 on the E200i storage controller if I'm not concerned about the battery-backed feature?

 

 

Eric Pretorious
2 REPLIES
Matti_Kurkela
Honored Contributor

Re: Enabling RAID5 on DL365 G5 Entry Model (411358-001)

There are multiple models of 128 MB BBWC, to cover all the various generations of SmartArray RAID controllers. You should use the part number to confirm the correct part: the HP PartSurfer website can provide parts descriptions (partsurfer.hp.com). The part 346914-B21 is the correct part for SmartArray E200i *and* SmartArray 6i.

 

The BBWC should never be a PCIe card, nor a mezzanine card; however, it can be called a "daughter card" as it is a small circuit board that will typically lie flat on top of the system board (with an integrated SmartArray controller) or on top of the RAID controller board (as with separate PCI-X/PCIe SmartArray controllers).

 

And the battery-backup feature is essential: when the module is used for write caching, and the server experiences a total power failure, the cache can hold more information than can be written to the disks using the remaining power in the system's capacitors. If there is no battery to maintain the cache over the power failure, the data held in the write cache at the moment of power failure would be lost. Because of this, the controller will monitor the condition of the battery and will disable the write caching functionality if the battery is not in acceptable condition.

 

Of course the controller cannot disable the RAID5 functionality if you have RAID5 sets configured - but with the write caching feature disabled, your disk performance will suffer.

 

In my opinion, leaving out the BBWC+battery module is a bad idea: the BBWC is not that expensive, and the performance improvement can be significant (depending on your workload, of course). It can make the difference between respectable performance and "this server sucks."

MK
epretorious
Regular Advisor

Re: Enabling RAID5 on DL365 G5 Entry Model (411358-001)

Thanks, Matti!

 

Eric Pretorious

Eric Pretorious