[SunRescue] Re: Software raid

[Robert Novak]

I thought I heard a "Joshua D. Boyd" say:
> 
> Has anyone here ever tried running software raid-5?  I need a new file
> server I guess (my current PeeCee one doesn't have enough drive bays or
> PCI slots).  Sun is an option, but PC is more likely.  

I've used Solstice Disksuite for RAID on Solaris, and it functions for
RAID-5, but does not perform too well. Of course I was building it up for
a higher demand environment than your typical home system (100 software
developers) so the hits I saw were more profound.

As another poster suggested, the Mylex PCI RAID cards can be had cheaply
(I have three, 3-channel wide scsi with 16mbyte cache, contact me offlist
if you're interested in one so I can dig it out) and if your OS supports
it you should be in good shape. They will give you better performance
although you would have to have a full-length pci slot available.

> Anyway, I'm wondering what the possibilities for software raid-5 are.  I
> know the computations are fairly intensive, but would something like a
> dual processor pentium (say dual 166) be able to keep up fast enough to
> saturate 100 mbit? How about an Ultra 1?  Ultra 5?  

If you really need 100mbps of nfs traffic, fairly consistently, you should
be able to justify hardware raid.

> Am I going to find that the cost of a good enough computer will be higher
> than the cost of a hardware solution?

I don't remember the numbers--could dig them out of 3-year-old email
archives if needed--but I had an Ultra 450, 4x300mhz cpu, 12 drives on 6
scsi buses (2 each) on 3 pci buses (1 card/2 scsi buses per pci bus) and
it still was not viable for my environment. I gave up and went to an
external hardware raid device. Any more I won't even touch software
RAID-5. RAID 0/1/0+1/1+0 is fine in software but beyond that, I won't even
give it the time of day. I have not used veritas raid5 so it might be
better, but for the cost of a license I can get a hardware controller :)

--Rob


-- 
Robert Novak, Indyramp Consulting * rnovak at indyramp.com * indyramp.com/~rnovak
        "And it's been a long December and there's reason to believe
           Maybe this year will be better than the last...." -- counting crows