Re: Software RAID, a bit OT

[Seth Mos <knuffie@xxxxxxxxx>]

At 13:20 17-7-2002 -0500, Ben Gollmer wrote:
> Hi storage gurus!
> This server is going to handle file sharing, e-mail, CVS, and a bug-tracking
> database for us. Our project has some rather large files so we need a good
> amount of storage space. I was planning to software RAID 5 the HDDs together
> for a total of 160 GBs. I have been enjoying XFS on my workstation but I
> know it has had problems with software RAID 5 in the past. Are these
> problems fixed now?

The only problems XFS had/has with raid5 are performance issues. They are 
not really problems in the sense that they break stuff. And performance 
fixes still occur every once in a while.

The real performance fix for raid5 is still in the works, untill that one 
is submitted everything still works and you can use it. I do it, I have a 
software raid5 with a internal log and I still don't consider it extremely 
slow in the sence that it is not usable. And the good thing is that it will 
only get faster in the future.

> We also considered trying to grab another 80 GB drive from somewhere and do
> a RAID 0+1 (still giving us 160 GBs storage) but I don't know if Linux
> software RAID handles this well.

This works just fine. I already built one for testing and it performed and 
worked well. Just create 2 raid 1 devices and stripe those 2 raid 0 devices 
together.
So something like this:

md0 = hda + hdb
md1 = hdc + hdd
md2 = md0 + md1

> Most of us run the -aa kernel tree on our workstations but I have no problem
> running SGI CVS kernels on the server if they are reasonably stable. Any
> input would be much appreciated :)

I am running the current CVS on some test machines but not on a production 
box yet. We decided to replace the broadcom gigabit cards(for intel e1000 
cards) so we don't need the tg3 driver from 2.4.19 anymore.

Cheers
--
Seth
It might just be your lucky day, if you only knew.