Before you start IBM Spectrum Virtualize update preparation, check the following items for every server that is attached to IBM Spectrum Virtualize that you update: 

GLYPH<SM590000> The operating system type, version, and maintenance or fix level 

GLYPH<SM590000> The make, model, and microcode version of the HBAs 

GLYPH<SM590000> The multipath software type, version, and error log 

For information about troubleshooting, see these websites (require an IBMid): 

GLYPH<SM590000> The IBM Support page on SAN Volume Controller Troubleshooting: 

IBM SAN Volume Contoller Troubleshooting 

GLYPH<SM590000> The IBM Support page on Storwize V7000 Troubleshooting: 

IBM Storwize V7000 Troubleshooting 

Fix every problem or “suspect” that you find wi th the disk path failover capability. Because a typical IBM Spectrum virtualize environment has several dozens of servers to a few hundred servers attached to it, a spreadsheet might help you with the Attached Hosts Preparation tracking process. If you have some host virtualization, such as VMware ESX, AIX LPARs, IBM VIOS, or Solaris containers in your environment, verify the redundancy and failover capability in these virtualization layers. 

## 9.4.5 Storage controllers preparation 

As critical as with the attached hosts, the attached storage controllers must correctly handle the failover of MDisk paths. Therefore, they must be running supported microcode versions and their own SAN paths to IBM Spectrum Virtualize must be free of errors. 

## 9.4.6 SAN fabrics preparation 

If you are using symmetrical, redundant, independent SAN fabrics, preparing these fabrics for an IBM Spectrum Virtualize update can be safer than hosts or storage controllers. This statement is true assuming that you follow the guideline of a 30-minute minimum interval between the modifications that you perform in one fabric to the next. Even if an unexpected error brings down your entire SAN fabric, the IBM Spectrum Virtualize environment must continue working through the other fabric and your applications must remain unaffected. 

Because you are updating your IBM Spectrum Virtualize, also update your SAN switches code to the latest supported level. Start with your principal core switch or director, continue by updating the other core switches, and update the edge switches last. Update one entire fabric (all switches) before you move to the next one so that any problem you might encounter affects only the first fabric. Begin your other fabric update only after you verify that the first fabric update has no problems. 

If you are not running symmetrical, redundant independent SAN fabrics, fix this problem as a high priority because it represents a single point of failure (SPOF). 

## 9.4.7 SAN components update sequence 

Check the compatibility of your target IBM Spectrum Virtualize code level with all components of your SAN storage environment (SAN switches, storage controllers, server HBAs) and its attached servers (operating systems and eventually, applications). 

Applications often certify only the operating system that they run under and leave to the operating system provider the task of certifying its compatibility with attached components 

