[CentOS] Re: raid5 crash

Bryan J. Smith b.j.smith at ieee.org
Mon Jul 11 03:55:02 UTC 2005


On Sun, 2005-07-10 at 16:46 -0500, Les Mikesell wrote:
> More likely it is a sign of age and unwillingness to replace equipment
> before it's useful life is over.

Not true.  I've been in many departments that get "hand me downs."  The
difference is when a department/organization cares about consistency
and/or configuration management and a department/organization that does
not care about consistency and/or configuration management.

Simple rule I use, _always_ request at least 2 of the same "hand me
down" systems.  More often than not, a department/organization is
unwisely distributing them one-to-a-customer, which is just ludicrous.
I'd rather have 2 slower systems than 1 faster.

> Even if you stay with the same vendor you usually can't buy the
> same design with the same parts for more than a year.  Which means
> that unless you buy them the day they come out, your next order
> is likely to end up being something different.

Which is why you _always_ request at least 3 of the same systems when
you buy new.  By the time it is a "hand me down," you should have at
least 2 working systems.

> Out of the gazillion kinds of equipment out there you can come up
> with a few in hindsight that have survived, but it's really a matter
> of luck regarding what you bought and installed.

Not if you don't buy 1 unit at a time.
Unfortunately, companies seem to not consider this.

> That's the real trick.  If you need something to work, keep a spare
> yourself, preferably a whole box that you can swap the drives from
> your production box into.

If I'm "white boxing," then I think that's an issue that should be more
formally addressed.  Again, this is not a money issue, some people just
make it that.  You make do with what you got, but you don't cross the
lines of good consistency and configuration management.

If that means not putting a high-end, but single, "hand me down" into
production, so be it.  I'm more worried about downtime than the ultimate
performance.  ;->

> 5 years isn't really that long a time in terms of business data, and
> I do recall seeing rumors in print a few years back that 3ware was
> going to stop producing the ide raid cards.

The only thing 3Ware stopped producing was its short-lived iSCSI storage
arrays.

And as far as 3Ware stopping producing the ATA RAID cards (e.g., the
7000 series), you can buy their newer SATA RAID cards (e.g., 8000 and
9000 series) and use their ATA-SATA converters.  Not ideal, but they are
officially supported by 3Ware.

But 3Ware is still very much producing the ATA RAID series (e.g., the
7000 series).  The 6000 series became dead the second 3Ware realized
that the RAID-5 firmware was never going to work correctly on it.  They
had already developed the 7000 series that massively improved RAID-5
performance.

Almost every single complaint I hear about 3Ware is the 6000 series and
RAID-5, a series _never_ designed for RAID-5.  BTW, I'm still using 6000
series cards for RAID-0, 1 and 10 without issue, some 6+ years after
release.

> They didn't and I'm not sure why, or why it was rumored that they
> would, but it still works out to a matter of luck every time you have
> to buy a replacement part and it still happens to be available.

3Ware is very well proliferated.

I really dislike when people "blanket assume" risk.  I like to get very
specific and when it comes to 3Ware solutions, you're talking a very
proliferated set of products with _full_ backward compatibility in
_every_ new version.

That's pretty low risk if you ask me.  ;->

-- 
Bryan J. Smith                                     b.j.smith at ieee.org 
--------------------------------------------------------------------- 
It is mathematically impossible for someone who makes more than you
to be anything but richer than you.  Any tax rate that penalizes them
will also penalize you similarly (to those below you, and then below
them).  Linear algebra, let alone differential calculus or even ele-
mentary concepts of limits, is mutually exclusive with US journalism.
So forget even attempting to explain how tax cuts work.  ;->





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