[HPADM] SUMMARY: SAN to SAN

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Date: Wed, 11 Feb 2004 17:02:37 -0500
To: <hpux-admin@dutchworks.nl>

Thanks to all who responded.
 
Basically, it is a complicated and expensive approach. I'm attaching
responses and a couple of vendors who are experts in this arena. So far,
mgmt decided not to go this route.
 
The question:
  For Disaster Recovery purposes we want to be able to keep two
identical SAN's in sync, so we run production locally and in the
hurrricane season switch to the remote SAN.
 
Please point to any documentation where I can get more info. Is anyone
doing something similar?
 
We are running SYBASE 11.9.2
HP-UX 11
HP Storage Works SAN
Vendors/contacts:
Rick Starr
954-227-5318
www.dasher.com <http://www.dasher.com/>
 
Dan Clark
Director of Sales
Wareforce
Direct 949-452-1436
Cell 714-745-3622
Home Office 714-969-7892
Responses:
This is a very complex issue. The simplest solution is to just
copy the data every evening after the database is shutdown.
But many DB's are 24x7 so this won't work. The next is a
SAN replicator, something provided by the SAN vendor.
It would be a high speed link with special firmware that
would keep the SANs in sync. If the SANs are not in the
same building, the solution gets very complicated. You would
have to provide a fast enough link speed (not LAN!!!) to keep
the data in sync at all times. Another solution is to have the
database provide a redundant location and not proceed until
all data was synchronized (performance hit).
Bill Hassell
Best regards,
Bill Hassell (blhconsulting@mindspring.com)
 
Arturo:
 
If you were using EMC disks, you would use an EMC software product
called SRDF. This duplicates at the disk level.
 
If you have an HP XP512 or XP1024 they have another product, which I
can't remember the name of, called something like "Busine Copy Continous
Access" (?).
 
Also there are are Oracle (and I suppose Sybase) products for remote
database replication.
 
You could also look at MC/Service Guard remote capability, called
Metro-Cluster, but I'm not sure that that will do it for you.
 
Where are you located that you worry about hurricanes?
 
    Stuart
 
Stuart Abramson | WABTEC Corp. | Wilmerding, PA
Off: 412/825-1434 | Cell: 412/417-1567 | email:
sabramson@wabtec.com
 
>Check out Veritas VVR. I have had experience with it and can vow that
>it works well. This should do the trick.
>
>--DD
Same here, the recovery would be similar to crashing of box. In other
words when you bring up Sybase on the other side it would go through
recovery of databases similar to shutting down the server with nowait.
Although we found that it requires lot of Network bandwidth in a very
transaction intensive environment.
 
Srikant Padma
Lead Database Engineer
Database Architecture
TLR Technical Services
 
 
For very short distances, where you can have both storage frames in the
same FC fabric, you can simply use Mirror/UX.
 
HP has layered products for Enterprise-class (XP48,XP128,XP512,XP1024)
storage systems to keep volumes synchronized between two frames. Some
modes are fully synchronous but only operate over (relatively) short
distances, < 1-2 km, while others are asynchronous and allow arbitraty
distances, limited only by the bandwidth between the sites.
 
The main product is HP StorageWorks Continuous Access XP.
 
                              Cheers, Tom

-- 
Tom Myers, Information Systems Engineer; Delphi Corporation, IS&S - KAT
Unix Admin, M/S CT200, P.O. Box 9005, Kokomo IN 46904-9005
E-Mail: tvmyers@eng.delcoelect.com  Voice: 765-451-0918
 
Arturo:
 
There is an entire consulting industry built around disaster recovery
replication via the SAN.  You should have no problem finding people
willing to take your money in exchange for designing a solution for you.
 
A good place to start looking for basic info is:
 
http://www.hp.com/go/ha
 
Follow the MC/ServiceGuard link at the bottom of the page.
 
You are probably going to be the most interested in what HP calls an
"Extended Campus Cluster".  Although they will try to bundle
ServiceGuard with it, it is NOT required.  What *is* required is someone
who knows enough about SANs to build what is called an Extended Fabric.
These let you locate your second data center up to approximately 100
kilometers away.
 
You can get some information about them from Brocade:
 
http://www.brocade.com/products/software/distributed_fabrics/index.jsp
 
Instead of the expensive dark fiber method Brocade uses, you could also
use a pair of fibre channel to IP routers and send the data over your
WAN.  (HP should have some recommendations on what they support.)
 
This HP document might be helpful:
 
http://docs.hp.com/hpux/onlinedocs/B7660-90013/B7660-90013.html
 
Once the infrastructure is set up, your hosts can now see both the local
disks and the remote disks.  Just mirror each logical volume via VXFS or
LVM so that half of it is on local storage and the other half is on
remote storage.  (This assumes that you have storage-level redundancy.)
 
To start up on the remote site, just disable the volume groups on the
local server, and enable them on the remote server.  (This assumes that
you have properly imported the volume groups on the remote server,
something that HP can go over with you if you're not already familiar
with it.)
 
This inexpensive method only works up to a limited distance (100km/62mi)
and the farther you go, the slower the system will respond to disk
writes.
 
If you need to go more than 100km, then you're looking at asynchronous
replication methods, which are much more complicated and expensive.
 
Whatever you do, avoid HP's SAN appliance, the "CASA".  This has been
reported to be too unreliable for a high availability environment.
 
  -- Steve
 
 
http://www.availability.sungard.com/
 
Enjoy !
 
Paul
 
HP sells Distributed Replication Manager for Storageworks SAN. It is
mucho dinero.
 
There are several ways to replicate data from one SAN to another. The
method depends
on your environment and requirements.  
 
HP has a product called,  "CASA" (Continuous Access Storage Appliances)
This product uses
and external appliance and replicates to a remote external appliance
over an existing IP infrastructure.
This product is easy to manage and uses existing HP VG's and LVM's. Nice
solution especially in an HP Unix/Windows
or Linux env. Information on CASA can be found on HP's web site. This
product is grate but can be pricey.
 
Another method can be as simple as LVM disk mirroring.
Obviously using disk mirroring depends on bandwith and/or distance.
Since mirroring waits for an acknowledgement of
a write before proceeding, Issues could arise if there were connectivity
problems between primary and remote sites.
If your remote site was within the Fibre Channel distance limitations
you could utilize dark fibre andat the LVM
level mirror from site to site.
 
A third method which I have deployed for several HP customers here in
South Florida is Veritas "Volume Replicator" 
This product is nice in that it does not require any additional HW just
Veritas VM and Volume replicator. It runs
on the hosts and is a good solid product. 
 
You mentioned storage works below are you actually using HP storage
devices ? Or is that just a reference to SAN management
software and Switches? If you are using EMC storage. EMC has a product
called SRDF. This product works on both the HW and
software level. Again works very well but a bit pricey.
 
It's been quite along time since I have had involvement with Sybase, But
I do know that Just as a reference, I have many customers using
Oracle. Oracle has a built in "Standby" Functionality. With this you can
forward all transaction logs as they are
created and apply them to the remote standby DB. This works great for
the DB but does bring over
any changes to applications or other file systems.
 
Information for any of these products mentioned can be found on their
company website.  You may I recall I have actually spoke
with you in the past. Quite a few years back I also worked a t Vitas.
Since I am an HP Channel partner and certified 
HP Server/Storage professional  I would welcome the chance to meet with
you and discuss any or all of these options with you.  
 
Hope this Helps.
 
Rick Starr
954-227-5318
www.dasher.com <http://www.dasher.com/> 
 
We are hoping to do this if we can get dark fiber between our main site
and the soon to be backup site. If we can do this we plan on doing OS
level mirroring over the SAN to keep thing simple.
 
- Justin
 
==================
 Justin Willoughby
 Computer Operations
==================
 
 
 
 
 
 
 
Arturo Matiz
305-350-6934
arturo.matiz@vitas.com <mailto:arturo.matiz@vitas.com> 
 
If at first you don't succeed, then skydiving isn't for you.
 
.
 
 
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