Re: drive optimisation

Well, I did say it would be my *ultimate* config... I never mentioned
anything about practicality :-) My real machines run multiple independant
drives, with Squid seeing them as multiple cache_swap partitions (i.e. no
RAID). This works well on my high level cache, the leaf caches at clients
all have only one 2-4 GB SCSI drive, and those are UltraSCSI (not Wide)
drives. This config works well for us.

I don't think I've ever swapped a drive for a freshly formatted one... As
long as the cache's performance doesn't take a dive I don't worry too much
about that. If the performance doesn't change, then it doesn't make sense
to go and do lots of box-tweaking.

Multiple controllers -- or better yet the hardware RAID controllers -- I
think only become beneficial when you start to get near the maximum
sustained transfer rate of your SCSI bus. Non of my caches are anywhere
near this, so I see the use of Wide SCSI as a way to add more drives
without filling up precious slots in the machine. I would love to see
someone come up with a wide SCSI CDROM drive just so that I could build
15-drive CD towers for clients and plug them in with one card. That's a
whole different story though :-)

Running MS Proxy is scary in itself! The only thing I like about MS Proxy
is that it is marketed, so vendors of web apps like to say "We support MS
Proxy". I see this as a good way to get apps proxy aware -- I just stick
my Squid on port 8080 and the web apps works just fine. And a little
tidbit about NT: It can't completely defrag. Apparently under NTFS you
can't move directories or some other file system element (NT is not my
specialty), so it can never be truely defragged.

        -Bill

On Thu, 8 Jan 1998, Alastair Waddell wrote:

> On Wed, 7 Jan 1998, Bill Wichers wrote:
>
> > My ultimate cache config would be RAID-5 config consisting of 9 GB
> > Seagate Cheetah drives all talking on a pair of UltraWide SCSI channels.
>
> I think considering the controller requirement, that maybe the 9GB drives
> are the best 'buy' at the moment (false economy to build the cache from
> more, smaller drives).
>
> So RAID 5 is mirroring right? My current philosophy is that the cache is
> is expendable, but then that's relative to what it costs, effectively, to
> fill it again.
>
> Are you then talking about two UW controllers running N*9GB drives up to
> the bandwidth that they can support ( <15 devices)? It'd be nice to be
> able to quantify when the need for additional controllers arises and
> amortise this into the cost of the cache setup.
>
> All of this fails to address the more subtle performance issues such as
> drive fragmentation/optimization etc. When did you last swap your cache
> drive for a freshly formatted one?
>
> This raises the incompehensible scenario of a MS proxy administrator
> running 'defrag' over their cache :) Then again, NT can do this in the
> background right? :):)
>
> Regards,
> Alastair Waddell
>
>
> >
> > -Bill
> >
> > On Wed, 7 Jan 1998, Alastair Waddell wrote:
> >
> > > I'd like to hear of experiences people have of drive configurations. Let
> > > say that this is for the garden variety Linux box with 128MB RAM and a
> > > P200 processor. Controller is Adaptec Ultrawide.
> > >
> > > I currently have one machine configured with 2*GB (Quantum XP34550W)
> > > drives. I need to add a 4 meg drive so will partition this to match the
> > > size of the existing drives making 4 equal partitions for squid.
> > >
> > > Next step will no doubt be the addition of a 9GB drive for which I will
> > > probably build a RAID0 (md) drive out of the 3 old drives of 8GB total
> > > size giving me 2 8GB drives.
> > >
> > > My question:
> > > - Is this a sensible/optimal upgrade path?
> > > - Should I really be adding another controller, if not now, then at least
> > > when I put the 9GB or whatever in later?
> > >
> > > Also, what are people's views on the Ultra versus the UW controller - the
> > > Ultras are a lot cheaper.
> > >
> > > General comments appreciated.
> > >
> > > Regards,
> > > -----------------------------------------------------------------------
> > > Alastair Waddell o Tel +61 3 96 400-400
> > > Technical Administrator o Fax +61 3 9222-1363
> > > CyberLabs o http://www.cyberlabs.com.au
> > > Queen Street, Melbourne
> > >
> > > + Virtual Services + DNS Maintenance + ISP Co-location + Internetworking
> > >
> >
> >
> >
>
> -----------------------------------------------------------------------
> Alastair Waddell o Tel +61 3 96 400-400
> Technical Administrator o Fax +61 3 9222-1363
> CyberLabs o http://www.cyberlabs.com.au
> Queen Street, Melbourne
>
> + Virtual Services + DNS Maintenance + ISP Co-location + Internetworking
>
Received on Thu Jan 08 1998 - 12:13:52 MST