[plug] SATA & Debian

[Craig Ringer]

Tim Bowden wrote:
> One of the motherboards I have been looking at from trinix.com.au is the 
>  Gigabyte GA-7N400PRO2 which has SATA RAID built in (Is this not /real/ 
> RAID?).

http://www.giga-byte.com/MotherBoard/Products/Products_Spec_GA-7N400%20Pro2.htm 


snippets:

Integrated Peripherals

    1. Silicon Image sil3112A controller
    2. GigaRAID ATA 133 RAID controller
    3. Realtek 8110S Gigabit LAN controller
    4. Realtek ALC650/655 Audio AC'97 Codec
    5. TI IEEE 1394 controller

Memory

    1. Type:Dual Channel DDR400/ 333/ 266- 184pin

Expansion Slots

    1. 1 x AGP slot (8x/4x-AGP 3.0 compliant), supports 1.5v display 
card only.

Bundle Software

    1. Norton Internet Security™
          1. Norton Anti Virus™
          2. Norton™ Personal Firewall
          3. Norton™ Privacy Control
          4. Norton™ Parental Control
          5. Norton™ Spam Alert

This wouldn't be my choice for an entry level server - it looks more 
like a midrange "geek board". I wouldn't run a server on an nForce2 
board. Do you need 1394/FireWire, sound, AGP, the Norton Interet Suite, 
or a less-than-stellar gigabit ethernet chip?

Perhaps a basic server board would be a better choice (price 
permitting). Typically this means onboard ATi video, no sound, no 
FireWire, often no AGP, a single P4 or Xeon socket, no SATA, etc. It 
also tends to mean stable and compatable.

While I don't especially like Intel's desktop boards, I love their 
server boards. For example:

http://www.intel.com/design/servers/buildingblocks/s845wd1-e/index.htm?iid=ipp_srvr+mthrbds_s845wd1e_srvr&
http://www.intel.com/design/servers/s875wp1-e/index.htm?iid=ipp_srvr+mthrbds_s875wp1e_srvr&

Assuming you can get ECC memory at reasonable prices, it might be worth 
considering. You'd need to confirm that these boards work without ECC 
otherwise.

You should also be aware, if you're considering adding high-speed drives 
later, that your PCI bus _will_ be a bottleneck. As you probably can't 
afford a board with 66MHz/64bit slots or PCI-X, I'd consider a board 
with the disk controller integrated into the southbridge except that I 
don't think  you can get any with SATA RAID in the southbridge yet 
(ICH5R uses an add-on sii chip for SATA AFAIK).

>  I have no idea yet how good it is but it seems to be an option. 
>  There are a number of SATA capable motherboards available for 
> reasonable money.

Yes, but reasonable quality? SATA support in linux is less than mature, 
and as I said earlier - what do you really gain from it in your situation?

http://www.google.com/search?q=sil3112A%20linux
http://www.siliconimage.com/products/sii3112.asp
http://www.siliconimage.com/products/overview_sii3112.asp

According to the sii3112 overview, it's driver-controlled software RAID 
with a few BIOS hooks. That has been discussed here before. Opinions vary.

Software
     * SATA Operating System Drivers: Windows 98, ME, NT4, 2000, XP and 
Linux
     * RAID Operating System Drivers: Windows 98, ME, NT4, 2000, XP and 
Linux
     * Supports RAID 0 (Striping) and RAID 1 (Mirroring) with Silicon 
Image Medley™ software RAID

If you decide you really want SATA, I strongly suggest more research 
into the real performance and reliability of the linux support for these 
chips.

> As for downtime, a little is ok.  I don't need hot swap.  Even though 
> the spin rates on the SATA drives is no faster than the PATA drives, the 
> larger caches (8mb v 2mb) has to make them faster for writes at least 
> (or have I got it all wrong?).

In that case, you might want to get 8mb cache PATA drives like the 
better Maxtor drives or WD JBs. They perform much the same as the 
(near-identical) SATA variants, tend to be a little cheaper, and remove 
the need for SATA support.

> Going with SATA also gives the ability to drop in 10,000 rpm disks in 
> about 12 - 18 months time when they are much cheaper and our needs are 
> greater.

Perhaps adding a PCI SATA controller later would be an option. You'll be 
able to pick one that's well supported under linux, buy drives after the 
SATA price premium is gone or reduced, and have a stress-free server in 
the mean time. You'll also have the option of evalutating other storage 
options - like SATA RAID - at that point, once you know if you'll really 
need it or not.

Then again, you'll have a bit of a bottleneck in the 33MHz/32bit PCI 
bus, especially if you're trying to send that data out over ethernet as 
well. I don't know for sure, but I expect the board you referenced just 
has the SATA controllers on the PCI bus anyway, so I doubt you gain much 
from using those over a PCI card.

You may find you're happy with the performance of the 72k RPM PATA 
drives and don't need to upgrade.

Honestly, I question the focus on SATA. It doesn't sound like your 
budget stretches to PCI-X or 66/64 PCI, so your disk performance is 
always going to be somewhat limited by the PCI bus. Whether this even 
matters in your environment I can't say. On the other hand, without high 
performance buses the utility of WD Raptors etc is somewhat reduced 
(though of course better seek times are nice, ditto SATA TCQ). Perhaps a 
more basic server might be a good idea, with a total upgrade in 12 - 18 
months if you need to dramatically improve performance? That way, you'd 
also get a hot-spare server (the old one) to use as a fallback.

I'm just throwing ideas around - you haven't said enough about the role 
of the server, it's performance needs, the budget, etc to do much more 
than that. Hopefully I've made a few useful suggestions for further 
research and thought.

Craig Ringer