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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