new server - 8 drives, hardware RAID, how to configure?

Putting together a new server for my home/office, and trying to decide how
to configure the drives.

Server will be an Active Directory server for a small LAN (5-8 users), but
primarily a data / media server for streaming DVDs, photos, music, etc.

Using an LSI Logic RAID controller with (8) Seagate SATA 1TB drives. Most of
the servers I configure are lower capacity with 6 SAS drives. I typically
configure 2 drives in a RAID1 configuration (system/OS array), 3 drives in a
RAID5 configuration (data array), and leave the 6th drive as a global
hotspare. I go with 2 RAID arrays instead of 1 big array with 2 partitions
figuring there is a performance benefit (simulaneous access on 2 different
RAID arrays should be quicker than simultaneous access on 2 partitions on
the same array, right?).

With this server, I'm considering using RAID6 since I have 8 drives to play
with and because of the capacity of the drives - even with a global
hotspare, it might take a day or 2 to rebuild the RAID5 in the event of a
drive failure. If a 2nd drive failed during that time, I lose my data. With
RAID6 I'll have 2 parity drives to play with.

So, I'm looking for opinions. Here are the options I'm considering:

(1) - 2 drives RAID1, 6 drives RAID6, no hotspare
(2) - 2 drives RAID1, 5 drives RAID6, 1 drive global hotspare
(3) - 7 drives RAID6, 1 drive global hotspare

Opinions?

lid wrote:
Kremlar kenjka:
Thanks for the detailed reply!

To provide a bit more detail, the RAID card I'm using is a LSI 8708ELP. I
will be using a battery module for the RAID card (won't be in for a couple
days).

Here's a thought... I'm using an Intel S3210SHLC motherboard for this
server. What if I installed a couple lower-capacity SATA drives (say 320GB)
on the motherboard's SATA RAID controller in a RAID1 configuration? That
would protect my system/OS partition, and leave me all 8 drives on my LSI
RAID controller for a 6TB RAID6 partition.

Thoughts?

That sounds OK with me...

I'm not very familiar with RAID10. Is the performance significantly better
than RAID6?

RAID10 has the speed of RAID0 and redundancy of RAID1... Basically, it's
like this:

- a lot of mirrors (2 drives in RAID1) are in one big stripe (RAID0)...

so you have something like this:

RAID0
--------------
II II II II II

II = RAID1

So, you have capacity of 5 drives using 10 drives at all...

I suggest you use SAS drives at 10krpm or 15krpm for system drives... Or
even consider using 2x flash drives... That way you'll get the best
performance...


There is no point in aiming for high performance for the OS/System
drives - they should not be accessed much except at startup. It's a
file server - all the relevant software and settings will be loaded at
the start. After that, there will be no urgent access to the OS
partition - about the only issue would be logging, and if you are
looking for large, detailed logs, put them in the data partition.

I'd go for a single small flash drive (4G is about 3G more than you
need) for the OS/partition, with a complete external backup once it is
configured. Everything else goes into the RAID (I'm planning on Linux
RAID 10, but I haven't tested it yet).

lid wrote:
David Brown kenjka:
There is no point in aiming for high performance for the OS/System
drives - they should not be accessed much except at startup. It's a
file server - all the relevant software and settings will be loaded at
the start. After that, there will be no urgent access to the OS
partition - about the only issue would be logging, and if you are
looking for large, detailed logs, put them in the data partition.

Sorry, didn't see that it was a server... In that case, some Linux
distribution ment to work as a NAS (like FreeNAS, or Open-E NAS)...

I'd go for a single small flash drive (4G is about 3G more than you
need) for the OS/partition, with a complete external backup once it is
configured. Everything else goes into the RAID (I'm planning on Linux
RAID 10, but I haven't tested it yet).

Yes, this is very good thing you're saying...

In fact, I did one prototype using 2GB USB stick for booting Windows XP,
using modified kernel files from Windows XP Embedded enabling Enhanced Write
Filter (EWF) disabling access to the flash drive once it's configured for
production (making the whole FS read-only and blazing fast)...


Here's an idea that might be interesting to try - use Knoppix (or rather
a remastered version with minimal packages, such as no gui), booting to
text mode and with the "toram" and "myconf" flags to copy the entire CD
to ram, and to store configuration on a USB device. That way you don't
need any harddisk for your OS, and all the software is already in ram.
It's also very secure - in the event of security breach, you can just
reboot. Updates are a little inconvenient, but that's not a problem for
a Linux system. There are various Linux (and BSD) distros aimed at
firewalls that run entirely from CD with no harddisk precisely because
of the security that gives.