Oracle DB and SAN

[Frank de Vries]

I forgot to mention that with the command
set you create a pair,
paircreate source lun target lun
Once the pair is setup you can activate
for the type of raid-mirroring

I will give the output of pairdisplay that
will explain a lot:
[root@orasrv2:]/HORCM/usr/bin<>>> pairdisplay -h
Model : Raid-Manager-XP/HP-UX
Ver&Rev: 01.08.00
Usage : pairdisplay [options] for HORC
-h Help/Usage
-z Set to the interactive mode
-zx Set to the interactive mode and HORCM monitoring
-q Quit(Return to main())
-g Specify the group_name
-d Specify the pair_volume_name
-d[g] [mun#] Specify the raw_device without '-g' option
-d[g] [mun#] Specify the LDEV# in the RAID without '-g' option
-c Specify the pair_check
-l Specify the local only
-m Specify the display_mode(cas/all) for cascading configuration
-f[x] Specify display of the LDEV#(hex)
-f[c] Specify display of the COPY rate
-f[d] Specify display of the Device file name
-CLI Specify display of CLI format
-FCA Specify the force operation for cascading CA_VOL
-FBC [mun#] Specify the force operation for cascading BC_VOL

Anyway, once your raid-pair is activated,
it is possible to failover (by the command horctakeover) to the target pair (which effectively is seen from a different node.

This works very well, but like I said, it is
still safer to shut the DB's, as you can never be certain the buffers will be written to datafiles during the takeover is finished.

We run Mc/Serviguard on top so we have the flexibility to not only swith nodes but also between the 2 XP systems. A fully fledges crossed-linked san failover system.

Basically plain-crash proof !!!
(Our Nodes and XP are in different buildings,
linked up with fibre)

Anyway I think you get the picture :))

[Sylvain CROUET]

What is the distance between you buildings? Would your solution still works over 50 km?

[Frank de Vries]

That is possible:
Depends on your fibre is multi or single mode and the thickness. See fragment below
I took from the Cisco manual for Certification:

What is the maximum distance fiber optic transmitters can operate at?
It depends on which LuxLink(tm) model you purchase. Normal transmission distances can vary from a fraction of a mile to 40 miles (60 Kilometers) or more. The maximum transmission distance depends on output optical power of the transmitter, the optical wavelength utilized, the quality of the fiber optic cable and the sensitivity of the optical receiver. In general single-mode based systems operate over longer distances than multimode systems. The approximate transmission distances for LuxLink(tm) systems are indicated in the table below.

-No. Wavelength Fiber Type Connector Transmission Distance covered**

-1 850 nm multimode ST up to 2 miles (3 Km)
-3 1310 nm multimode ST up to 6 miles (10 Km)
-7 1310 nm single-mode FCPC up to 20 miles (30 Km)
-8* 1310 nm single-mode ST up to 20 miles (30 Km)
-9 1550 nm single-mode FCPC up to 40 miles (60 Km)


regards,

[Sylvain CROUET]

If the distance between my two sites is over 100km, what kind of solution can I use?

[Frank de Vries]

I see what you are getting at.

Well then you need to inmplement an intermediant groundstation, that amplifies the signal. Equipment like this can be purchased from Nortel networks for instance.

Or alternatively, you can rent a public or private line from a telecom provider and they will do it for your.

We hire a T1 line from French telcom that connects our Brussels servers with our Stockholm server, were the standby server is , and no one realises that. It looks as if it stand in the room next door. Just a matter of bandwith and budget !!
(Technology is not the restraining factor ,
believe me)

[Sylvain CROUET]

You are not faced with delays due to the distance? You still have a real time bit to bit copy of the database?

[Frank de Vries]

Well the functional answer to your question
is no, no delays at all, as to user it is transparent.

However, for the nitty gritty technician , naturally there is an propogation delay due to distance and ground equipment and corresponding dataload. But this
propogation delay is measured in a dozen or
so milliseconds, so that is neglectable.

To give an example. A link via Satelite,
for large video images , thus up 37thousand km up, and again 37K downlink, takes 0.75 second to do the roundtrip.
So what would the difference between 10km and
100 km for a data packet, it is transparent for the user.

More important is that the bandwidth is not
saturated. You can have longer delays on
a local lan.

Also , Of course we have a reduntant line via an alternative path, with automatic switchover if timeouts are not respected.

[Sylvain CROUET]

So, if I summarize your configuration: you have two servers with a database, a primary server and a backup server. Each server is connected to a SAN built with XP arrays. Bit to bit replication is made in real time by HP StorageWork Business Copy XP between the XP arrays. There is no impact on production.
Am I right?