perc 9 series fastpath feature for database data

Hi,

I need advice regarding RAID Controller configuration for PostgreSQL data.
Known common best practices:
- RAID cache at least 512MB
- BBU is must have
- cache mode = write back
- disk write cache mode = disabled for hdd and low level ssd and disk write
cache mode = enabled for ssd enterprise level with backup condenser
- barrier=0
- vm.dirty_background_bytes=67108864 and vm.dirty_bytes=536870912 for RAID
with 512MB cache.

But now I want to ask about special configuration for Dell PowerEdge RAID
Controller (PERC) 9 series with 2Gb write cache due to Fastpath feature
listed in Dell's documentation:

> FastPathis a feature that improves application performance by delivering
> high I/O per second (IOPs) for
> the Solid State Drives (SSD).

To enable FastPathon a virtual disk the Dell PowerEdge RAID Controller
> (PERC) 9 series cache policies
> need to be set to Write-Throughand No Read Ahead. This enables FastPathto
> use the proper data path
> through the controller based on command (read/write), IO size, and RAID
> type.

Using dell enterprise level SSD's in RAID 10 for PostgreSQL data is
supposed.

It seems that with this raid controller and ssd's the best practice would
be slightly corrected:
- cache mode = write through
- disk write cache mode = disabled
- barrier=0
- vm.dirty_background_bytes=16777216 and vm.dirty_bytes=134217728

Wouldn't this configuration be dangerous in case of power-loss disaster and
especially isn't it dangerous to use barrier=0 with Write Through raid
cache mode?

Thanks in advance.