RE: Firewire Cards/Drive and Linux RAC
- From: "Peter Miller" <Peter.Miller@xxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 18 Jun 2004 16:44:48 +0100
Your just showing off now!
Thanks for the info
Pete
-----Original Message-----
From: Matthew Zito [mailto:mzito@xxxxxxxxxxx]
Sent: 18 June 2004 16:39
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: Firewire Cards/Drive and Linux RAC
"You like me! You really like me!"
Both firewire and SCSI support more than two nodes - though its only
generally practical with Firewire. While the firewire disk is dual
ported, there are a couple of tricks you can use to get more than two
nodes hooked up to it. One is to buy a firewire hub - that can get you
to four nodes. The other way, which is uglier, is that most of the
firewire cards on the market that have multiple ports effectively
implement a firewire hub within the card. That is to say, all of the
ports on a card exist within a single firewire network and a single
controller chip. So, what you can do is cable two hosts directly to
the disk, and then cable a third host to another port on one of the two
already-connected hosts, and it will get access to the disk. Of
course, should that intermediary host lose power, both hosts will lose
access. I think the max in either scenario is four nodes - we don't
scale our firewire clusters any larger than that, because the only
reason we get that big is benchmarking, and we use proper servers and
storage for that.
SCSI is hard - you need either a SCSI hub or a disk array with many
ports, and those are hard to find.
Fibre Channel is designed for this - basically, you need an array and a
hub or switch. Used, you're probably looking at $8k-10k for some hbas,
old fibre channel storage, and a hub or switch. Fibre is expensive -
stick with firewire if you're just playing around.
Also, another option that is not officially supported, but works, is
iSCSI. It's a bit of a hassle, but you can get the iSCSI target
implementation from http://www.ardistech.com/iscsi/ . You basically
create raw devices, and then export them via the driver. Then you can
use the downloadable cisco iscsi initiator to access them - they show
up as local disks, fairly cool. In order to get any reasonable
performance, you're going to need Gigabit ethernet. Again, its a
hassle, but you can hook a lot of nodes up this way at a very low
incremental cost.
Thanks,
Matt
--
Matthew Zito
GridApp Systems
Email: mzito@xxxxxxxxxxx
Cell: 646-220-3551
Phone: 212-358-8211 x 359
http://www.gridapp.com
On Jun 18, 2004, at 11:18 AM, Peter Miller wrote:
> Cheers Matt,
>
> you are my 10g RAC hero guru. I'll get onto ebay straight away.
>
> Once I've got some experience and success with the firewire set-up,
> I'll
> have a go at the SCSI cluster. I'm considering at getting a pair of
> Adaptec 39320A-R cards and a Dell PowerVault 221S with cluster/split
> bus
> module.
>
> One thing that does bug me is that both the firewire and SCSI have
dual
> ports that limit them to 2 nodes. Not very scaleable. Ignoring NAS (
> i.e. NetApps), what h/w supports 3+ nodes ? Is it SAN ?
>
> If so any ideas about the price differential between SCSI and SAN. I
> guess I'm looking at £3.5k for the SCSI array and RAID cards. How much
> for a SAN implementation? Any ball park figures appreciated
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