best possible GJOURNAL device?

[Garrett Cooper]

On Thu, Apr 26, 2012 at 10:16 AM, Wojciech Puchar
<wojtek at wojtek.tensor.gdynia.pl> wrote:
> http://www.vikingmodular.com/products/arxcis/ddr3/ddr3.html
>
> or ZFS ZIL device for ZFS fans.
>
> anyone know exactly how it is visible and how it works?

In general devices like these that I've dealt with in the past are
presented as SATA or SAS devices, but some devices require additional
drivers (take Ramdrives devices for instance).

> isn't BIOS clearing out memory on reboot?

Depends on the BIOS, the settings set in the BIOS, etc.

> FreeBSD is but it can be patched easily.

I wouldn't depend on volatile memory working in a non-volatile manner
unless it's battery backed (which companies like Ramdrive, STEC,
Viking, etc do) and in which case all you're doing (depending on how
the device is designed) is delaying writes out to non-volatile
(NAND/NOR flash) or another non-volatile medium (USB thumbdrive?
etc... I vaguely remember seeing a vendor doing something "clever"
like that...).

> How to get DRAM controller mapping i mean what DIMM is at what address?

What is located where should be opaque if the designer designed it
properly (otherwise a driver will need to be added to interface with
the device if the vendor is trying to be clever or is not fully
conforming to ATA/SCSI standards).

Thanks,
-Garrett