Online Capacity Expansion, RAID, Etc.

Nikolas Britton freebsd at nbritton.org
Sun May 29 16:25:09 PDT 2005


Wojciech Puchar wrote:

>> to be starting the array in a RAID 1 config using 2 drives, I will 
>> then migrate, and grow, the array to RAID 5 using the ORLM and OCE 
>> features of the board when more space is required. FreeBSD, 
>> RELENG_5_4, will NOT be install on this array, it will be on a 
>> separate RAID 1 array using the motherboard's on-board SATA RAID 
>> controller.
>
>
> how about buying two 4-port SATA PCI board to your server and use 
> software RAID.

2x PROMISE TX4 PCI-X SATA Controller ($65) $130
PROMISE SX8-O PCI-X SATA Controller Card $164:
8 SATA Ports
PCI-X

HighPoint RocketRAID 2220 PCI-X SATA-II RAID Controller $249:
8 SATA Ports.
PCI-X.
XOR Engine.
64bit LBA.
HotSwap.
HotSpare.
Online Capacity Expansion.
Online RAID Level Migration.
Can connect two of them together with a jumper cable for a 16 Port RAID 
card.
RAID Management Program, Will email me if RAID is degraded, auto rebuild 
of RAID, etc.
The company supports FreeBSD and provides* drivers for FreeBSD, Also I'm 
happy with a past product I bought from them.

*Read the author section of the hptmv man page and go here:
http://www.highpoint-tech.com/USA/bios_rr1820a.htm

The backplanes are $115 each

$115 * 2 + $249 - $164 = $315, The diffrence in price for a hardware 
RAID vs software RAID.

>
> lots of test showed that "hardware" RAID system isn't faster.
>
>
> and think twice before making RAID5. it IS slow on writes. 

Right now the bottleneck is are LAN. We are at 100Mb/s switched, on all 
ports.

> or using vinum make RAID5 for partition that will store mostly large 
> or rarely-written files, RAID1 for others, and no RAID for temporary 
> space like swap space (or maybe RAID1 for this too if keeping system 
> up is so important, not only data protection).

The swap and system slices will be on there own 80GB RAID 1 array, a 
RAID 1 for the data storage array is out of the question because it eats 
up half the space and I don't need that kind of fault tolerance for the 
data, 1TB vs 1.75TB, though a small RAID 0 slice might be a good idea. 
It could be used for a working drive and then setup a script to move it 
to the RAID 5 at the end of the day or something... I'll have to think 
about that, thanks.

Here's the bottom line for why I don't want a software RAID. I have no 
experience with vinum or other software based RAID techniques on the 
UNIX platform, I've done it with windows and was unimpressed. It would 
take me 6 months at least to understand everything, test it, brake it, 
and for it to gain my trust but I only have about a month to get this 
thing online for production use. I've built many hardware based RAIDs in 
my life but none that where this big and had features like ORLM and OCE.

Thank you for replying,
    Nikolas


More information about the freebsd-questions mailing list