Summary: Is installing OS on a StorEdge A1000 recommended?

Hello Everyone,

I'm sorry that it took so long to write this summary!

For the most part, people did not recommend installing the
operating system on the A1000.  One person said that they
have the OS installed on an a3500 which is attached to a E4500
and it works fine.  Someone else said that they have installed
the OS on the A1000, and they don't think this is the way to
go because it's difficult to configure and maintain.

Everyone said that you must use the Raid Manager software
in order to control the A1000 array.  Some people said that you
could use Volume Manager on top of Raid Manager if you want to.

Most people suggested using the A1000 for application files or
data.  They didn't recommend putting any part of the OS (not even swap)
on the A1000 because if something happened to the A1000, you couldn't
boot the machine even to single user mode.    They recommended
putting the OS and all essential software (RM6, backup software etc)
on the internal disks.  This gives the benefit of being able to
at least boot the machine if the A1000 dies.  

I also talked with a couple different people at Sun, and they did not
recommend putting the OS on the A1000 either.  Some of the reasons
include: controller being a single point of failure; if an array
firmware upgrade fails, you can't boot; and possible performance problems
(although, Sun did say I should be ok having some swap on the array).

I ended up installing the OS and RM6 on the internal disks, and mirrored
them with DiskSuite.  I put extra swap space on the A1000.

Some other interesting points people mentioned are:
- Putting the OS on the A1000 requires extensive modification of the startup
  cripts. The reason is that the A1000 is not recognized by the boot
  monitor, it is accessible only after drivers are loaded early in the boot
  sequence.

-Performance: All backend operations (syscalls, driver-loads,
 paging for OS functions, ...) have to squeeze over SCSI pipe.
 Also, A1000 H/W RAID5, while better than S/W RAID5
 (according to my tests, write-times for large volume AND large
 number of files, 7 times faster than S/W RAID5), is still 1/6th
 the speed of  S/W RAID1 (Also my tests). A1000 offers RAID1,
 I beleive. So if you have to do it that way, at least use R1.

- Running Sun RAIDManager 6.x S/W HAS resulted in corruption of the rootfs 
  ( would only mount read only forever after) on the A1000 it controls 
  while adding disks after the fact (Very labor-intensive recovery).

- if something happens to your OS (which includes /var and swap - 
  depending on how you setup the extra swap space) and it's on
  the A1000, you'll have to restore OS as well as Raid Manager software before
  you can even access A1000.  

- Use and internal disk for the OS. When things go wrong (with A1000) 
  you can get the OS running without 
  compromising the data on the storage device and then install the 
  drivers for the extra hardware.

-  obey the rule that if you're booting from CD or from a network-root, 
   you should be able to access the
   slices the system needs for booting up into - at least - single user mode
   with nothing more than plain Solaris.

-  Consider the situation where your A1000 ... fries all of the disks
   you used to set up your boot device. Sun comes in, replaces the hardware,
  and you're left with, essentially, a blank disk. Your OS went away with your
  failed disks, and unfortunately, the software to configure the A1000 went
  away as well! Sounds like re-install time....... If your OS is entirely on
  an internal disk, you're still looking at a restore, but you've completely
  bypassed the "rebuild the box" stage.


Thank you all very much for your help!
Shristophe Dupre, Kevin Buterbaugh, Steve Beuttel, Jim Taylor, Kim, Charlie,
Gary Carr, David Evans, Andrew Merrill, Clifford Thurber, Floria Schlaich,  
Stan Pietkiewicz, Brian Kerr, Bill Hebert and  Stefan Molnar.

Nicole

--- Original post 

Hi Everyone,

I have an E4500, with two internal disks, and A1000 array,
and a T3ES array.  I would like to know what people think
about installing the OS on the A1000 array.  I talked with
someone at Sun, and they do not recommend it.  My gut
feeling is that it would be better to install the OS on
the internal disks, and put /var, extra swap, and third
party software (except perhaps the software controlling the
A1000 and T3ES) on the A1000.

I searched the archives and found one user who is against it, and
some people who do it.  

If you have done this, what problems have you had? How difficult
is it to get back up and running when something goes wrong.

Finally, for those who have done this, did you use Volume
Manager or Raid Manager Software to control the A1000?
Seems like a catch 22 to do the install.


Thanks in advance for your help and opinions!!


Nicole Skyrca
AppliedTheory Communications Inc.        Phone: 315-453-2912 x5861
100 Elwood Davis Road                    Fax: 315-453-4594 
Syracuse, New York 13212
 
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