Windows administrators are spending more of their time managing SANs and iSCSI storage. This guide is a compilation...
of troubleshooting tips related to networked storage in a Windows infrastructure.
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|SAN||Return to Table of Contents|
Companies are increasing their use of iSCSI SANs -- high-speed storage networks that interconnect different kinds of data storage devices with associated servers on behalf of a larger network of users.
This introduction to Windows-based SANs will get you started with networked storage.
Microsoft has a plan for making things easier for Windows administrators adopting SANs. It's called Simple SAN, and it's designed to allow systems administrators and their staff to deploy a SAN in practically no time.
Along the same lines, reducing the overhead of a SAN implementation is a key factor for smaller Windows shops. These companies are trying to realize their savings by managing their SAN with one software package and one person instead of with several people.
|Troubleshooting SAN||Return to Table of Contents|
Troubleshooting a SAN? You can save yourself a lot of work by verifying that the problem is a SAN issue, not a generic storage issue, then starting your troubleshooting at the SAN's center.
If multiple servers are able to access the same logical disks in your SAN, the SAN is not properly configured. And if you run into a problem configuring a SAN into a server cluster, here are some of the error events that you might see in the system logs.
Very few SANs are limited by the speed of the connections. A typical enterprise SAN is much more likely to be constrained by port limitations, considerations of topology and architecture and management issues than by raw speed. This tip takes a look at the arrival of 4 GB Fibre Channel.
Each server on a SAN needs its own boot drive. To avoid problems stemming from booting from a SAN, you need to designate as many boot drives in the storage array as there are servers accessing that storage, and the server must have access to the correct boot disk. This requires setting the host bus adapter boot BIOS to the address of the disk or LUN.
The most common symptom of a boot-from-SAN problem is that the system can't locate the boot partition and boot files. While booting Windows from a SAN can be an incredibly hardware-specific and detailed process, it's something that Windows administrators are learning to do.
This tip outlines the six factors involved in sizing SAN storage for Windows Server 2003. And this tip describes how R2's Storage Manager for SANs emphasizes the basics.
Many administrators who want to set up a SAN opt to get the software from the same company that makes the SAN hardware. But the cost of this convenience (aside from the price tag) is being locked into using a particular vendor's management package. If it's possible to build a network disk array using commodity components, why should the software be a hindrance? Now there's a storage management operating system called OpenFiler 1.1 which uses open-source componentsto turn any server with a disk array (or any other attached storage the server can see) into a SAN appliance in minutes.
Just about every SAN uses SCSI drives, which typically perform better than IDE hard drives. It's almost impossible for an administrator to allocate storage in a SAN, build a cluster or set up a hardware-based RAID array without understanding how SCSI works.
|iSCSI||Return to Table of Contents|
Whereas a traditional SAN required a fibre optic-based infrastructure with expensive switch equipment betwen a host server and the storage controllers, an infrastructure based on the IP-based storage network standard known as iSCSI can leverage commonly available Ethernet switches, cables and standard networking protocols to communicate between servers and storage devices. By carrying SCSI commands over IP networks, iSCSI facilitates data transfers over intranets and to manage storage over long distances.
Many companies whose storage needs are dramatically growing are deploying iSCSI SANs rather than purchasing more servers. However, the process for deploying an iSCSI SAN can be a complex one. Here's a step-by-step guide for deploying an iSCSI SAN.
|Troubleshooting iSCSI||Return to Table of Contents|
If you're having problems with the performance of your iSCSI storage network and you're using Microsoft's iSCSI Initiator, this checklist on troubleshooting iSCSI can run down the possible causes.
One of the things to check in an iSCSI SAN is that all the equipment is set up to allow the use of jumbo frames of 9,000 bytes.