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Re: Help New system with Adaptec 1430sa controller

On Tue, Nov 20, 2007 at 03:23:35PM -0500, Stephen Woodbridge wrote:
> I was going to get the 3ware card, but with only 4 drives it seemed like 
> overkill and from what I read running RAID 10 is faster then RAID5 in a 
> 4 drive config. So I opted for the Adaptec controller. <sigh>

It is never overkill to get supported hardware.  raid10 is certainly
less processor intensive since it only does comparisons not XORs.  It
also gets less disk space (raid 10 gets you 50% of your total disk
capacity, while raid5 gets you all but one disk worth, so 75% in your
case).  As for performance, well the raid0 may give you better
performance than raid5 in some cases, but possibly worse in others.
After all the raid5 has 3 out of 4 disks available for reading, while
raid10 has 2 or 4 depending on if the raid1 reads from alternate disks
or not (I think linux raid1 does the alternate reads but not sure).
raid10 is certainly simpler and safer I would say.

> I did find
> http://kmuto.jp/debian/d-i/
> and it looks like amd64 etch-custom-1013.iso - kernel version 2.6.23 + 
> experimental e1000e driver D-I iso recognizes the the raw drives 
> regardless of how the raid contoller is configured. I guess I will 
> reconfigure it as JBOD so the controller doesn't try to manage them.
> So with 4 x 750GB drives, how can I get debian to build a RAID10 and 
> make it bootable. This probably isn't the list to ask a general question 
> like this, but ... here it is :)

Well the boot loader can boot from raid1, but not raid0 or raid10 or
raid5 (unless you have hardware raid in which case it becomes
transparent).  So you would probably have to make a small (100MB or so I
would suggest) raid1 partition on a pair of disks to boot from, and then
you can do whatever you want with the rest.

It is also posible to do raid1 volumes and then use LVM on top (LVM can
do striping like raid0 but you would have to tell it to do so at
creation time as far as I know).

Len Sorensen

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