Tony Pearson is a Master Inventor and Senior IT Architect for the IBM Storage product line at the
IBM Systems Client Experience Center in Tucson Arizona, and featured contributor
to IBM's developerWorks. In 2018, Tony celebrates his 32th year anniversary with IBM Storage. He is
author of the Inside System Storage series of books. This blog is for the open exchange of ideas relating to storage and storage networking hardware, software and services.
(Short URL for this blog: ibm.co/Pearson )
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I always try to catch a session from Jim Blue, who works in our "SAN Central" center of competency team. This session was a long list of useful hints and tips, based on his many years of experience helping clients.
SAN Zoning works by inclusion, limiting the impact of failing devices. The best approach is to zone by individual initiator port. The default policy for your SAN zoning should be "deny".
Ports should be named to identify who, what, where and how.
While many people know not to mix both disk and tape devices on the same HBA, Jim also recommends not mixing dissimilar disks, test and production, FCP and FICON.
The sweet spot is FOUR paths. Too many paths can impact performance.
When making changes to redundant fabrics, make changes to the first fabric, then allow sufficient time before making the same changes to the other fabric.
Use software tools like Tivoli Storage Productivity Center (Standard Edition) to validate all changes to your SAN fabric.
Do not mix 62.5 and 50.0 micron technology.
Use port caps to disable inactive ports. In one amusing anecdote, he mention that an uncovered port was hit by sunlight every day, sending error messages that took a while to figure out.
Save your SAN configuration to non-SAN storage for backup
Consider firmware about two months old to be stable
Rule of thumb for estimating IOPS: 75-100 IOPS per 7200 RPM drive, 120-150 IOPS per 10K RPM drive, and 150-200 IOPS per 15K RPM drive.
Decide whether your shop is just-in-time or just-in-case provisioning. Just-in-time gets additional capacity on demand as needed, and just-in-case over-provisions to avoid scrambling last minute.
Avoid oversubscribing your inter-switch links (ISL). Aim for around 7:1 to 10:1 ratio.
Don't go cheap on bandwidth between sites for long-distance replication
Next Generation Network Fabrics - Strategy and Innovations
Mike Easterly, IBM Director of Global Field Marketing, presented IBM System Networking strategy, in light of IBM's recent acquisition of Blade Network Technologies (BNT). BNT is used in 350 of the Fortune 500 companies, and is ranked #2 behind Cisco in sales of non-core Ethernet switches (based on number of units sold).
Based on a recent survey, companies are upgrading their Ethernet networks for a variety of reasons:
56 percent for Live Partition Mobility and VMware Vmotion
45 percent for integrated compute stacks, like IBM CloudBurst
43 percent for private, public and hybrid cloud computing deployments
40 percent for network convergences
Many companies adopt a three-level approach, with core directors, distribution switches, and then access switches at the edge that connect servers and storage devices. IBM's BNT allows you to flatten the network to lower latency by collapsing the access and distribution levels into one.
IBM's strategy is to focus on BNT for the access/distribution level, and to continue its strategic partnerships for the core level.
IBM BNT provides better price/performance and lower energy consumption. To help with hot-aisle/cold-aisle rack deployments, IBM BNT provides both F and R models. F models have ports on the front, and R models have ports in the rear.
IBM BNT supports virtual fabric and HW-offload iSCSI traffic, and future-enabled for FCoE. Support for TRILL (transparent interconnect of lots of links) and OpenFlow will be implemented through software updates to the switches.
While Cisco Nexus 1000v is focused on VMware Enterprise Plus, IBM BNT's VMready works with VMware, Hyper-V, Linux KVM, XEN, OracleVM, and PowerVM. This allows single pane of management of VMready and ESX vSwitches.
In preparation for Converged Enhanced Ethernet (CEE), IBM BNT will provide full 40GbE support sometime next year, and offer switches that support 100GbE uplinks. IBM offers extended length cables, including passive SFP+ DAC at 8.5 meters, and 10Gbase-T Cat7 cables up to 100 meters.
Inter-datacenter Workload Mobility with VMware vSphere and SAN Volume Controller (SVC)
This session was co-presented between Bill Wiegand, IBM Advanced Technical Services, and Rawley Burbridge, IBM VMware and midrange storage consultant. IBM is the leader in storage virtualization product (SVC), and is the leading reseller of VMware.
Like MetroCluster on IBM N series, or EMC's VPLEX Metro, the IBM SAN Volume Controller can support a stretched cluster across distance that allows virtual machines to move seamlessly from one datacenter to another. This is a feature IBM introduced with SVC 5.1 back in 2009. This can be used for PowerVM Live Partition Mobility, VMware vMotion, and Hyper-V Quick Migration.
SVC stretched cluster can help with both Disaster Avoidance and Disaster Recovery. For Disaster Avoidance, in anticipation of an outage, VMs can be moved to the secondary datacenter. For Disaster Recover, additional automation, such as VMware High Availability (HA) is needed to restart the VMs at the secondary datacenter.
IBM stretched cluster is further improved with a feature called Volume Mirroring (formerly vDisk Mirroring) which creates two physical copies of one logical volume. To the VMware ESX hosts, there is only one volume, regardless of which datacenter it is in. The two physical copies can be on any kind of managed disk, as there is no requirement or dependency of copy services on the back-end storage arrays.
Another recent improvement is the idea of spreading the three quorum disks to three different locations or "failure domains". One in each data center, and a third one in a separate building, somewhere in between the other two, perhaps.
Of course, there are regional disasters that could affect both datacenters. For this reason, SVC stretched cluster volumes can be replicated to a third location up to 8000 km away. This can be done with any back-end disk arrays, as again there is not requirement for copy services from the managed devices. SVC takes care of it all.
Networking is going to be very important for a variety of transformational projects going forward in the next five years.