Here are a few rules of thumb:

• Use a lot of spindles, but not large RAID sets. Concatenate many smaller RAID sets into a single logical unit number (LUN) using host software or LUN virtualization within the storage hardware.
• Use low-latency paths to storage. Fibre Channel uses a packet-based network that allows for a full duplex back end. On a SCSI bus, only one thing can happen at a time. Using dual-pathed Fibre disks, the read command on one side and a write command on the other side of the disk are queued simultaneously.
• Spread out the I/O load by putting several host bus adapters (HBAs) in a server to load balance I/O across all the paths. Tools like Veritas Volume Manager or Solstice DiskSuite can help to do this by creating a single LUN from many spindles on each path. With 2Gb paths and four HBAs, you can get almost 800MB/sec to the LUN.
• Use the proper RAID level for the log and database. Log files should be on RAID 0+1 (RAID 10) and databases should be on RAID 5 (or RAID 0+1, if your budget allows).

-Chris Poelker, storage architect; co-author, Storage Area Networks for Dummies

Additional Questions:
	April 2005:	Can you use SATA, Fibre Channel and ATA disks on the same SAN array?
	March 2005:	Can you save a Shark (IBM Enterprise Storage Server) configuration for disaster recovery purposes?
	February 2005:	Is it true that Ethernet networks don't track and acknowledge requests, but Fibre Channel networks do?
	January 2005:	I just bought a computer with a SATA disk drive and two CD-ROMs. Can I put a Zip drive on the CD-ROM's IDE cable?
	December 2004:	Do governing bodies restrict which types of archiving media can be used for compliance?
	November 2004:	In a Solaris 9/VxFS VxVM environment, how do I transparently migrate files to a SATA partition in a Fibre Channel SAN?
	October 2004:	With tape backups, do I need an original and one copy or two copies?
	September 2004:	What should we do first: upgrade backup software and hardware or implement a SAN?
	August 2004:	What will happen to the Storage Management Initiative Specification (SMI-S) in 2004?
	July 2004:	Is there a cheaper alternative to Veritas VCS or Sun cluster for Sun on Sparc and x86 platforms?
	June 2004:	Can you tell me how implementing a network-attached storage (NAS) gateway could help with storage consolidation, as well as with direct-attached storage (DAS) issues?
	May 2004:	As an industry rule, how many storage administrators should be on staff per terabyte of data?
	Apr 2004:	How do you shred data stored on write once, read many (WORM) media?
	Mar 2004:	Why do you say that "bearings and the actuator arm mechanics used in the higher priced drives are rated for a more useful life than both IDE and ATA?"
	Feb 2004:	The theoretical maximum number of Fibre Channel Arbitrated Loop (FCAL) drives on a loop is 127, but what's a practical number?
	Jan 2004:	What are the variables to consider when determining how many host bus adapters (HBAs) are required per server?
	Dec 2003:	What kinds of tools can help me find files that are no longer used?
	Nov 2003:	Can you please explain what content-addressed storage (CAS) is, and what it's used for?
	Oct 2003:	What do you think of serverless backup?
	Sep 2003:	How do NAS blades in director-class switches work? Will they become popular?
	Aug 2003:	Which is best for consolidating storage in an SAP environment: SAN or NAS?
	Jul 2003:	I have 60% free space on 10,000 PCs. Can I consolidate it by mounting it as a volume and using a login script to map it to the desktops?
	Jun 2003:	Can you describe the steps that a single byte takes when going from memory to a spinning spindle and back again?
	May 2003:	What trends do you see in open-systems backup and recovery environments?
	Apr 2003:	What tools can we use to replicate domestic and overseas databases to one another?
	Mar 2003:	We're building an HSM solution to which we'll write 100GB+/month and store it for seven years. Do you think we should use CD, DVD or tape?
	Feb 2003:	I want to consolidate 10TB+ of files onto one system. Would you recommend products from EMC, NetApp or one based on Microsoft's SAK?
	Jan 2003:	I'm out of disk space on my Sun server running Oracle. Is NAS a good choice?
	Dec 2002:	File server cluster vs. network load balanced vs. DFS: What's the best method for file server HA?
	Nov 2002:	What are the pros and cons of storing user files on a RAID array with either ATA or SCSI drives?
	Oct 2002:	Can you do a LAN-free data transfer by giving an IP address to a FC adapter? Does it decrease the speed of data transfers to LAN speeds?
	Sep 2002:	What is the average amount of hosts for a centralized system to backup at one time?
	Aug 2002:	Why doesn't my mail client software create a lock for e-mail files if it's reading it off a NAS device? Which non-EMC NAS devices provide a gateway to connect to an EMC Symmetrix SAN?
	July 2002:	What does storage pooling mean? What do you think of it?
	May 2002:	What is the difference between a NAS gateway and a SAN appliance? Is tape still the best for archiving media files? Does it offer a lower TCO than disk?
	Apr 2002:	In terms of feed speed, what does that measurement refer to? Is it from the primary storage to the secondary storage? Does it stop at the write speed on the tape drive?
	Mar 2002:	How can you use solid-state disk (SSD) to accelerate SAN performance?