HPE Smart Array P440ar: Modular Form, Cache and HBA Mode
The Smart Array P440ar is an HPE RAID controller fitted to a range of ProLiant servers. The two letters at the end of the name matter more than anything else in it.
The "ar" suffix means it is not a standard card
The point that decides whether this part is right for your machine.
HPE Smart Array controllers come in several physical forms. A standard PCIe card fits any suitable slot. An "ar" variant is a modular controller that fits a dedicated position on the system board rather than a general PCIe slot.
Three consequences.
It is server-specific. A modular controller fits the chassis families designed for it and not others, regardless of the Smart Array generation.
It does not consume a PCIe slot, which is the reason the form exists — it leaves general slots free for other cards.
Standard and modular versions are not interchangeable. A standard card will not fit the modular position and the reverse is equally true.
So the first thing to establish is which form your server takes. Our controller guide covers identifying what is fitted, and the management controller reports it without opening the machine.
The cache module is a separate part
The most common omission when ordering a Smart Array controller.
Controller cache on this generation is typically a flash-backed write cache — a cache module plus a capacitor pack that provides enough energy to write cache contents to flash when power is lost.
Three things follow.
Cache module and capacitor pack are separate parts from the controller, with their own part numbers, and a used controller may arrive without either.
Without working backup, the controller runs write-through. Every write goes to disk and is acknowledged only when the disk confirms, which collapses write performance — and nothing appears broken. No failed drive, no array error, just a slow server.
Capacitor packs are consumable. They degrade with time and heat, which makes this a scheduled replacement rather than an unexpected failure.
This is the single most useful thing to check on a ProLiant that got slow with no explanation. Check it before buying faster drives.
RAID mode and HBA mode
Smart Array controllers of this generation can generally present drives directly rather than as arrays.
RAID mode is the default — the controller manages arrays and presents virtual disks.
HBA mode passes drives through individually, which is what software-defined storage and some file systems require because they want unfiltered access to physical drives and their health data.
Two cautions. Switching modes is destructive to existing array configuration, so decide before building. And a controller in HBA mode gives up its cache benefit entirely, since there is no array for it to cache. Our RAID versus HBA guide covers when each is right.
Moving arrays between servers
Array configuration is written to the drives rather than only to the controller, which makes this more recoverable than people expect.
A set of drives moved to another server with a compatible Smart Array controller is generally recognised, and the configuration can be imported. Three cautions.
Move all drives together and record their order.
Firmware levels should be compatible between source and destination.
Have a working backup first. This usually succeeds and is not something to attempt without a fallback — our backup guide covers why an untested backup is an assumption.
This is also why a failed controller is frequently recoverable rather than catastrophic.
Drive compatibility
Two points specific to Smart Array.
Firmware validation is strict. HPE Smart Array controllers are among the stricter platforms at checking drive firmware — a non-HPE drive may work, may be flagged in iLO, may not report predictive failure warnings, or may be refused during a rebuild. Our HPE drive guide covers this.
Carrier generation is separate. Whether a drive physically seats depends on the Smart Carrier generation matching your chassis, which has nothing to do with the controller. Our compatibility page lists both by platform.
Before you order
Your ProLiant model and generation, and whether it takes a modular or standard controller. Whether you need the cache module and capacitor pack, which are separate parts. Whether you intend RAID or HBA mode. And if you are replacing a controller holding an existing array, say so — firmware compatibility matters for importing the configuration.
Common questions
What does the ar suffix mean?
It indicates a modular controller that fits a dedicated position on the system board rather than a general PCIe slot. That makes it server-specific, and standard and modular versions are not interchangeable in either direction.
My ProLiant got slow with no errors. What should I check?
The controller cache backup. Without a working capacitor pack the controller runs write-through, which collapses write performance while nothing appears broken — no failed drive, no array error, just a slow server. Check this before buying faster drives.
Is the cache module included?
Not necessarily. The cache module and capacitor pack are separate parts with their own part numbers, and a used controller may arrive without either. Capacitor packs are also consumable, degrading with time and heat.
Can I run it in HBA mode?
Generally yes on this generation, which suits software-defined storage wanting unfiltered access to physical drives. Two cautions: switching modes is destructive to existing configuration, and HBA mode gives up the cache benefit entirely.
My controller failed. Have I lost the array?
Usually not. Array configuration is written to the drives rather than only to the controller, so a compatible replacement generally recognises them and the configuration can be imported. Move all drives together, record their order, and have a backup first.
Send us your ProLiant model and generation, and tell us whether you need the cache module and capacitor pack.
