Re: Iseries and External storage

Rob
Thks for sharing the info .

I believe DS8K can be directly connected to the isystems via Fibre channel
adapter whereas for SAN one has to go through switches /routers etc
...So are there issues in that case in terms as which is faster. though
faster would depend on I/Os per second (IOps) , Megabytes per second (MBps)
and Latency .


On Thu, Oct 8, 2009 at 4:57 PM, Robert Gray <robert.gray@xxxxxxxxxxxxx>wrote:

We have been on external storage using DS8K technology for some time now
and have actually been looking at other platforms which may be more price
competitive than the IBM storage line. What we have found surprised even our
Intel brethren who were shouting they could get storage from EMC or
Equillogic for a fraction of what it was costing us.
The first thing to understand is tiered storage. Tier one storage is 5 9s
storage (99.999% uptime) and tier two is 4 9s, so on. Running you production
LPARs on external storage is going to require 5 9s tier one storage, no room
for argument. I am not certain if Hitachi offers support for system i but it
is very expensive so we did not even consider it. We looked at EMCs Symetrix
DMX storage and compared some functionality to IBM DS8K technology, both
tier one (It was advised by Dell who sells EMC to stay away from their CX4
offering for attaching to system i).

Both Symetrix and DS8K have all the bells and whistles: redundant servers,
redundant power, lots of cache, hot spares, non-disruptive upgrades and
expansions, virtual disk technology, RAID and mirroring at the storage
level. EMC may come in a smidge less after all hardware and licensing is
accounted for but after looking at a shop that implemented EMC DMX and
comparing to our shop, we have noticed IBM superior in a couple of areas.

First, is service. Understand that storage guys and system i guys like to
point the finger when a problem arises. When the finger pointing starts and
you are attaching IBM hardware to IBM storage, IBM can appoint a 'crit sit'
manager to force cooperation and solve the problem. EMC and IBM support may
not play well together.

Second, shortly after you move to external storage, you will start to look
at technology like iASP, FlashCopy (Snap in EMC speak), PPRC (asynchronous
replication), partition mobility, switched disk (failover). IBM has a
toolkit and has made significant advancements recently to allow easy
management of your DR or HA environment. EMC may have made advancements here
but previously, all scripting to initiate any of these tasks were done
in-house and required skill and management to keep it working.

All in all, you have do a lot of homework to determine capacity,
allocation, connection, growth, DR or HA needs, etc. Both EMC and IBM will
come in and flatter you with technological wizardry. In the end, you have to
decide. We like storage and hardware from one company and after looking at
IBM Lab Services PowerHA, copy services toolkit and HA Assist for our DR/HA
needs, we are going to continue with something we KNOW works very well with
system i and other open systems platforms, DS8K.

Also, look at lower end tier two storage for non critical storage needs
(DS4K, XIV, with VIOS or SVC attachment but that's a whole different
subject.

Good Luck

Robert



-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:
midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Neeraj J
Sent: Thursday, October 08, 2009 10:07 AM
To: midrange-l@xxxxxxxxxxxx
Subject: Re: Iseries and External storage

We are presently running multiple 570's with V5R4 and are planning to

upgrade to 595 .
We have Approx 40-60TB of Disk space. In the Upgrade process we are
looking for DS8000 or using the SAN storage which is used by other

systems

also.
What are the benefits and drawbacks of DS8000 compared with other SAN
storage (EMC , Hitachi etc).
Is using internal disk a better option than DS8000 or SAN ?


Any thoughts /comments are welcome

Thks in advance

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