[rescue] A Question about Snap Servers
velociraptor at gmail.com
Sun Aug 1 19:45:36 CDT 2004
On Sat, 31 Jul 2004 17:15:36 -0400, Phil Stracchino
<alaric at caerllewys.net> wrote:
> On Sat, Jul 31, 2004 at 01:56:41PM -0500, Jonathan C. Patschke wrote:
> > On Sat, 31 Jul 2004, bitrot wrote:
> > >does anyone have a nice SIMPLE way of setting up raid 1
> > >on solaris 9.
> > 1) Create a tiny (10MB or 20MB) slice (I'll call this an mslice) on
> > each disk for the metadb and a big slice on each disk to hold your
> > data (I'll call this a dslice).
> > 2) Do metadb -a -f mslice1 mslice2 mslice3 # You really need three tiny
> > # slices.
> More is better. Three is the *minimum*.
> I quote:
> ... The majority consensus algorithm accounts for the
> following: the system will stay running with exactly half or
> more replicas; the system will panic when less than half the
> replicas are available; the system will not reboot without
> one more than half the total replicas.
> In other words, three is the minimum number of metadb replicas with
> which it remains possible to boot the system after losing a replica.
Yes. But performance degrades after some not so large number
of copies. When I was working at $big_network_co, we usually
limited the number of copies to about 8-10.
Nothing like having to work on another sys admin's boxes when
they took the "3" as the max number, when a metadb's disk
decides to crap out. :-(
My other favorite thing was the sys admins who decided to use
slice 2 as the slice to use in the metadevice. If you use slice
2 for this purpose, and that disk fails, when you replace it with
a disk of the exact same geometry, it thinks it is the same,
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