ASM "disk" replacement

We are using ASM for 10.2.0.4 RAC on Linux x86-64 and will need to
replace a number of disks in the storage array.

 

I am wondering if anyone here has had any "interesting" experience with
this sort of thing - good or bad.

 

This can also be a sanity check on my embryonic "plan".  I just heard
about the need for this today and need to come up with a plan.  We don't
have to do this soon, but it absolutely must be done well before the end
of the year.

 

This may be complicated (or simplified) a bit by the fact that we have a
sort of "minimal ASM" setup.  ("New-fangled gizmos anywho - don't
entirely trust 'em." - the OraSaurus in me says.)

 

The basics:

 

Only datafiles and tempfiles are on ASM - in a single diskgroup.

Redo is on "real" raw devices, not ASM.  Archive destinations on OCFS2
filesystem.  RMAN backups to NAS.

2.5+ TB database - hot, mostly with massive 24xforever inserts.  (This
beast generates 200+ GB of archive on a slow day.)

The six existing ASM "disks" are actually RAID-10 sets striped and
mirrored in hardware - about 500 GB each.

Only "external redundancy" in ASM.

Physical (exclusive) standby also on ASM - different hardware and
location, but same layout, but a different diskgroup name.

[Network link between primary and standby is rather busy - bandwidth
about 50% utilized just by log shipping.]

Notable downtime is not an option.

 

In theory, this should be easy (famous last words) - alter diskgroup ...
add <some new "disks"> drop <some old "disks">;  

 

Adding the new replacement "disks" (with similarly sized/performing
hardware RAID-10 sets) and dropping the old ones in a single "alter
diskgroup" command *should* minimize the ASM rebalancing.

 

We would likely do this first on the standby, then on the primary once
the standby "reorg" is complete.

[Hopefully, we will have a complete production mirror - RAC, standby and
all, with somewhat weaker hardware though - to test all this on first.]

 

So, does anyone have any relevant experiences, horror stories, caveats,
hearsay, et cetera to share?

 

Thanks for any info!

Don Granaman

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