I'm setting up a RAID 10 config on a Linux (CentOS 5.1) box, a machine that does not have a SATA controller on the motherboard.
I bought an Areca ARC-1120 with the intention of just using it in JBOD mode, as a plain SATA II controller with the actual RAID management done by Linux. Now that it's time to do the actual set-up, I'm conflicted.
The RAID config will be composed of 4 SATA II disks, but I bought an 8-disk controller to keep my options open. This machine is on a UPS, so I'm not concerned about disk corruption due to the ARC-1120 buffer being lost.
I've heard repeatedly that the Linux software RAID is rock-solid. I've set up a software RAID before and it was a straightforeward process. (I do not yet have experience recovering from a disk failure.) The downside is increased CPU utilization and general system complexity. The upside is independence from any particular RAID controller.
Praise also seems to be plentiful for the Areca RAID controllers. I wouldn't be using one of their main selling points, the XOR engine, in a RAID 10 config, but the disks would be unified at the hardware level. The downside is dependence on Areca for quality of fimware, for diagnostic software and on unknown actual disk layout. The upside is that the on-board 256MB cache and synchronized NCQ should make for more efficient I/O. (That's my fact-free assumption, anyway.) Plus, I like the simplicity of presenting a single disk to the operating system.
Regarding performance/optimization: the ARC-1120 has a more intimate knowledge of the underlying hardware; the Linux kernel's software-based RAID has a more intimate knowledge of the workload being handled. I have no idea which type of RAID management would provide the better net performance.
My workload is mostly STR-dependent (Samba files server on a Gigabit LAN) I/O, for whatever that information is worth.
So, what to do? Hardware or software? Are there gotchas and/or benefits that I'm not taking into consideration? Has anyone reading this done gone both routes and have a basis for comparison?
Any guidance toward one option or the other would be appreciated.