Limit on number of raid arrays in a HP P420i

Question

On the spec sheet of P420i HP raid controller, it says the maximum number of logical drives is 64 with 512 mb cache or above.

But what is the limit of the number of arrays one can create.

For example, if I have a server with 24 SFF SAS Disks and I want my OS to see 24 separate disks without any RAID or .. since I am forced to use the controller, with RAID 0 (which I know doesn't make sense), than, can I have 24 different arrays with 1 logical drive in each of those arrays?

Solution

You won't have any issues with this, as the maximum number of allowed logical drives on the controller exceeds the number of disks in the server.

I like to caution against doing this, as I have with Hadoop and ZFS solutions. Multiple separate RAID0 logical drives is not the same as having a JBOD controller. There are implications for hot-swap events because a failed disk really becomes a failed logical drive. This can cause device renaming issues at the OS level.

If this is a permanent need, I'd suggest using one of HP's purpose-built SAS HBAs, like the H220 (LSI-based)...

However, if you update the firmware on your existing P420i, you will see an option to create multiple RAID0 arrays automatically if you use the HP Smart Storage Administrator, as you're requesting. This was put in place specifically for this use case.

Auto RAID 0 – creates a single RAID 0 volume on each physical drive specified, enabling the user to select multiple drives and configure as RAID 0 simultaneously.

Comments

[omar-ali]

Excellent that you say what you say - i don't really want to use the p420i but am restricted to using HP Servers. So the H220 (or H221) basically is a controller that just presents the disks as is?

[ewwhite]

The HP H220/H221 are HP-branded LSI controllers that are meant for this type of situation: Hadoop, ZFS, Windows Storage Spaces, VMware vSAN and any other case where you need to pass raw disks to the OS level.