SUMMARY: Enterprise 6500 configuration

From: Theresa Russo (
Date: Tue Jul 21 1998 - 06:06:17 CDT

Thanks to all for your quick response:

        Jeff Wasilko
        David Thorburn-Gundl
        James Ford
        Brian Styles
        Tim Carlson
        Matti Siltanen
        Peter L. Wargo
        Brett Lymn
The general consensus to the first question is that there is no added
value and it may introduce problems. I did not provide enough
information on questions two and three.


We have just received an Enterprise 6500 server with 2.5GB memory and
three Fibre Channel Clarion Storage Arrays and have been asked to
configure it as follows:

        / and small /usr on internal disk
        full /usr on storage array
        2GB of swap on each storage array

Can anyone help me with the following questions?

        1. What are the benefits of having the /usr partition
mounted from the array?

        2. Is this the right amount of swap space?

        3. Does anyone have a recommended configuration for this
type of system?


> Can anyone help me with the following questions?
> 1. What are the benefits of having the /usr partition mounted from
> the array?

None, and it's likely to cause problems. Depending on what
interface card the Clariion uses (the one from Sun or a 3rd
party), you might not be able to boot from the CDROM to fix a
problem or do an upgrade.

IMHO, the OS should never be on an external array if you can help


I could imagine having /usr on the arrays, since one hopes that they are screamingly fast, but I don't see why (except that you mentioned only one internal disk, which means you cannot mirror except on the arrays); /usr is usually not a terribly busy filesystem. Meanwhile, having a small /usr on the internal disk sounds like you want to be able to boot from just the dinternal disk if the array is sicko; this doesn't sound like a really manageable plan to me (but that's just MHO :-) If you plan to load up /usr/local with stuff, then you could certainly put *that* out on the array, but it would, I should think, become a real chore to keep things updated in both copies of /usr (patches are my first thought), especially when one is hiding under the other.


How big is the internal disk? I don't actually know if I would mount /usr on the array since it contains system commands. What happens if your array crashes yet all /usr is stored there?

Now, you could have /usr/openwin, /usr/local/, /usr/etc stored on the array. If your array crashed, you couldn't run openwin from the boot drives but you would have access to all files in /usr, /usr/bin, etc.


Well, call me old-fashioned, but I'd have / /usr /var and at least some swap on _conventional_ disks. You need only some glitch in the controlling software for your super-whizzbang arrays and you no longer have a machine which will run at all. Apart from other inconveniences, this would make debugging such a problem rather tricky! And, if these arrays are 3rd-party, Sun won't help...

I guess the advantage _ought_ to be speed - transfer rates aren't all that hot from conventional drives. Then again, you'd hardly be transferring Trilobytes/sec from these areas (if you've got enough memory/swap)


I don't understand why you would want /usr out on the array.. I think that is a really bad idea. If you ever want to reconfigure the array, you may have to end up moving /usr around..


Question - can a sun both off a drive in the clariion fc raid? (we had made a datageneral mini boot off a clariion raid (older scsi version) -> with the system disks mirrored...worked very well :-)


1. None, unless you plan on loading lots of junk under /usr (not a good idea, IMHO). The internal disk should be at least 4Gb, probably shipping with 9Gb now. Plenty big for your root, /usr, /var filesystems.


Well, the FC disks are faster, but read on for my thoughts We just put in a 64CPU/64G E10000 with 10 A5000's. Generally, if your're using Sun arrays, it's neat to use a disk as boot (works great under 2.6), and another disk on a different array as a boot mirror. In any event, mirroring the boot drive is a *good* idea. What kind of disk-management software are you using?


Not much, possibly some speed but that may or may not happen. I can see no reason for just putting /usr on the array. If you are going to put them on the array then put both / and /usr. Having a backup copy of / & /usr on an internal disk is handy just in case the array goes down. Also you may have difficulty installing / & /usr onto the array because the CD image does not probe for LUNs other than 0 so you may not see all the stripes on your array. ----

Terry Russo Mercury Computer Systems email: Voice: (978) 256-0052 X192

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