[Gllug] Hardware comparisons

[Alain Williams]

On Sun, Mar 25, 2007 at 09:42:53AM +0100, James Roberts wrote:

> - SCSI drives are available in exact replacement sizes. This reduces the 
> pain of failed disk replacement, especially when using software RAID. 
> But for a server you normally need hot-swap and it is cheaper to get 
> good hardware for this with SCSI. The sata hot-swap hardware we have 
> seen is poop.
> 
> - software raid requires much more management. If you want to be able to 
> send Fred down with a new drive, then use SCSI. If using software raid, 
> then you need to be very careful about the sizes of the volumes so that 
> they are easily re-established on a replacement drive that is now 40 
> sectors smaller than the original form the same company. Been there. Yes 
> in theory all this can be worked around with LVM etc but at some point 
> we need to make a profit.

Hot swap is not a requirement (an infrequent hour downtime won't kill,
especially if it can be scheduled - which is 1/2 the point of mirroring),
the managability argument is important.

> Just a note, we have stopped building servers for clients (though we 
> 'craft custom machines' for special purposes still). By the time you 
> cost in a server-class mb, ecc ram, raid controller, array box, drives, 
> dual hot-swap psus (we are talking server no?) then the cost of building 
> almost always beats the cost of buying and includes a 3-year on site 
> service.

Agreed, I used to but don't any more. However: different vendors (DNUK
& CCL in this case) have differnt 'offerings' and the question was mainly
about how to compare the two.

We'll likely be going DNUK since the customer has heard of them and so
''has a nice warm feeling about them'' - which matters a lot.
The trouble is that specifying/QAing hardware is something that I don't
do often, and many of the details seem to change every few months which
makes giving informed advice very difficult.

-- 
Alain Williams
Linux Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256  http://www.phcomp.co.uk/
Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php
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