[KLUG Members] alternate redundancy v. cost

[Adam Tauno Williams]

> All businesses seem to be obsessed with redundancy.  Most admins usually
> choose to purchase the "expensive" servers with redundant power supplies
> and redundant raid5 scsi data storage.  For a reasonable server like
> this one can expect to spend 3.5-10 G$'s depending on the specifics of
> number of processors, amount of memory and drive space.  

A little on the high side.

> Has anyone
> considered using two less expensive hosts to get the same effect.

Yes, thats what the IBM x300 is for.

> I know there are methods/projects to get network filesystems to
> synchronize but have not tried them.  

THEY ALL SUCK!

> Two inexpensive machines with some
> of the newer sata drives and workstation quality memory and mobo's may
> produce some decent reliability results.  

In my experience the answer to this statement is "NO"

> All services performed by
> these servers could be configured to be manually switched over to the
> other at a moments notice.

True.  But the manually part sucks, that will need to happen while your on
vacation.

> I guess I am just asking for opinions.  I would tend to lean against it
> but the idea sounds intriguing to me.  Money is always a factor
> unfortunately.  The cost of the commodity stuff is just so low relative
> to the scsi and server mem stuff.

It depends.  I run non-storage intensive service (intranet, dns, dhcp, smtp
relay, etc...) on small "cheap" hosts,  I have I think 7 IBM x300s.  Then for
storage intensive apps like file serving, IMAP, & database - ALWAYS BUY A REAL
BOX.

But that doesn't mean you can't "cheat".  I have an IBM x300 with two 120G IDE
drives I use for file serving - becauase there is fileserving, and there is
fileserving.  Lots of time people just want crap available on the network and
it is 90% read-only, or huge transaction files that are process and discard.  I
create those shares on the poopy little IBM x300,  while real data volumes and
home directories live over on the netfinity 5000 on hot-swap SCSI RAID.  With
DFS people don't even need to know they wandered from one server to the other.

And there is a thought - that netfinity 5000 is *OLD*.  I've looked at them on
e-bay for $200-$300 dollars;  I'd buy another one in a heart beat, the thing is
a data serving gorilla, and CPU and such doesn't really matter for something
like Samba - two 500MHz PIIIs can handled HUNDREDS of clients and never break a
sweat; especially in one of these tweaked out beasts.  Used netfinity hardware
is abundant and excellent.

Other apps like LDAP, DNS, etc... are naturally distributed - an x300 here, an
x300 there, another one over yonder.  Need more performance?  Add more cheap
servers.