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Date:      Wed, 28 Jun 2006 18:22:04 -0400
From:      Francisco Reyes <lists@stringsutils.com>
To:        Nikolas Britton <nikolas.britton@gmail.com>
Cc:        Marc =?ISO-8859-1?B?Ry4=?= Fournier <scrappy@hub.org>, Atom Powers <atom.powers@gmail.com>, Ted Mittelstaedt <tedm@toybox.placo.com>, chad@shire.net, freebsd-questions@freebsd.org
Subject:   Re: Are hardware vendors starting to bail on FreeBSD ... ?
Message-ID:  <cone.1151533324.192719.61382.1000@zoraida.natserv.net>
References:  <20060620060845.U1114@ganymede.hub.org> <LOBBIFDAGNMAMLGJJCKNOECCFEAA.tedm@toybox.placo.com> <ef10de9a0606211118v43e0c3f4g1631c6c617bb6970@mail.gmail.com> <20060621183832.H1114@ganymede.hub.org> <ef10de9a0606211523h566b86c7u636889d826ce38e5@mail.gmail.com> <20060621195523.I1114@ganymede.hub.org> <df9ac37c0606220834h3d122cc9n4804674d5ce7009b@mail.gmail.com> <cone.1151484011.696455.14057.5001@35st-server.simplicato.com> <ef10de9a0606280318r6847c403uf57fb5f1da452a66@mail.gmail.com>

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Nikolas Britton writes:

>> Dont get me wrong.. I can get approval to go SCSI since our
>> machines need at least 1T+ (the storage machines)

err.. should have say "can't get approval" to go SCSI.. We are using SATA.
  
 
> Why? 1TB and up is a SATA niche.

Correct.. that is what we use.

> You can buy 3 SATA arrays for the price of 1 SCSI array


Yup. SCSI drives are 3 to 5 times more expensive than SATA.

>.... Also... gigabit Ethernet is only 125MB/s
> (Max) and and a single SATA drive can easily transfer at 50MB/s*.

But RAID can possibly do more than 125MB/sec if doing large sequential 
files..

When I last tested on a 100Mb switch vs a 1000Mb switch, the performance 
difference in our case (rsyncing data from Maildir) was around 25% to 30% as 
measured over a week. And this is mostly lots and lots of small files. That 
tells me that even with SATA we are able to go over the 100Mb limit.
8 Disks in RAID 10, with 2 hot spares.


> limiting factor is probably going to be your bus with arrays/GigE so
> SCSI is pointless unless you can take advantage of SCSI's TCQ with
> high random access I/O loads

If we could afford it I still think SCSI would be usefull. It is not only 
about raw throughput, but how quickly you can get the data to the apps or 
to disk. Specially in a database or Maildir enviroment where there is lots 
of I/O going on.

> *I just tested this with two Maxtor SATA drives the other day:
> dd if=/dev/disk1 of=/dev/disk2 bs=4m. It dropped off to about 30MB/s
> at the end but my average read/write was just over 50MB/s.

But that is mostly sequential work.. I think for sequential work SATA is 
definitely the way to go.. is when you get into the random I/O that 
supposedly SCSI outshines SATA.



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