What is perc controller and why i need perc controller to configure raid?

Junior admin

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Dear Friends,
We planned to buy one dell power edge server. In the quote of the server i seen this perc controller.
I don't know what is perc controller, and why it need to configure raid. Please share your knowledge guys.

Thanks,
Junior admin.
 

izx

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Jan 17, 2016
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Perc is Dell's "brand name" for hardware RAID controllers. You need one if you plan to do hardware RAID.
 

mstone

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"Power Edge Raid Controller". Someone else's RAID controller with a Dell label slapped on it for branding.
 

Terry Kennedy

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"Power Edge Raid Controller". Someone else's RAID controller with a Dell label slapped on it for branding.
It is usually a bit more complex than that, although generic firmware is often available if you want to de-brand a Dell card.

Dell's servers often have an "integrated" slot which takes a different version of the PERC card (often with a model number ending in "i" for Integrated). That slot doesn't accept generic cards (the BIOS will usually complain about "unrecognized card in integrated slot" or similar). If your planned usage will use most or all of the available PCIe expansion slots, using the integrated controller may mean the difference between a workable configuration or needing to move to a larger model to get additional slots.

It is possible to save money by purchasing the controller elsewhere (like eBay), but bear in mind you no only need the controller but chassis/backplane-specific data cables, the battery or capacitor backup unit and possibly a battery cable and/or bracket as well. And of course there's no Dell warranty on an eBay purchase.

If you or your company is buying from Dell, presumably you're doing it for ease of configuration, warranty and support and not price - just get the offered PERC controller and call it a day.

One word of caution - Dell sometimes offers SATA drives as the default in some configurations. If you're going to spend the money for a PERC card, make sure you get SAS drives as well. Some configurations offer hot-swap and non-hot-swap models. You'll probably want to get the hot-swap version.
 

Junior admin

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Feb 18, 2016
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It is usually a bit more complex than that, although generic firmware is often available if you want to de-brand a Dell card.

Dell's servers often have an "integrated" slot which takes a different version of the PERC card (often with a model number ending in "i" for Integrated). That slot doesn't accept generic cards (the BIOS will usually complain about "unrecognized card in integrated slot" or similar). If your planned usage will use most or all of the available PCIe expansion slots, using the integrated controller may mean the difference between a workable configuration or needing to move to a larger model to get additional slots.

It is possible to save money by purchasing the controller elsewhere (like eBay), but bear in mind you no only need the controller but chassis/backplane-specific data cables, the battery or capacitor backup unit and possibly a battery cable and/or bracket as well. And of course there's no Dell warranty on an eBay purchase.

If you or your company is buying from Dell, presumably you're doing it for ease of configuration, warranty and support and not price - just get the offered PERC controller and call it a day.

One word of caution - Dell sometimes offers SATA drives as the default in some configurations. If you're going to spend the money for a PERC card, make sure you get SAS drives as well. Some configurations offer hot-swap and non-hot-swap models. You'll probably want to get the hot-swap version.
Hi Terry kennedy,

Thanks for your valuable information.

I am wondering if i get, why SAS drives i need instead of SATA?. Any advantages that having over SATA drives?
 

gea

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You should add some informations about the planned platform and use case.
For newer filesystems like ZFS you do software raid where you need a dumb HBA to build a Raid without problems like write hole problems.

If you use older filesystems ex Windows + ntfs, you may prefer a hardware Raid.
For critical data you should add a BBU to reduce the write hole problems of conventional Raid.
 

Terry Kennedy

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I am wondering if i get, why SAS drives i need instead of SATA?. Any advantages that having over SATA drives?
Some Dell systems use SAS expander backplanes. The PERC controllers are generally 8-port units, so if a chassis offers more than 8 drive slots, there is likely an expander in there. SATA drives behind a SAS expander can have problems during error recovery in some cases. Dell sometimes uses a SAS/SATA interposer in the drive caddy to work around this (generally only on dual-port backplanes).

If all of the above just sounds like gibberish, get the Dell SAS drives if you can afford the price premium over Dell SATA drives.