[CentOS] Centos/Linux Disk Caching, might be OT in some ways

> There are concerns that everyone's currently fast performing LVM file
> systems will suddenly become doggish once barrier support is included
> and in some cases it will be true. Using a separate SSD device as a
> journal can help in some cases.
>

That's only if you are using ext3/ext4 and data=journal. Are SSDs faster 
than bbu nvram cards?