Search Term Tuesday – May 26th Edition

by dave on May 27, 2008

This is the second edition of the same post. Evidently, WordPress doesn’t like it when I fat-finger in Firefox 3.0 Beta 5. Grrrrr…..

So, what is “Search Term Tuesday” (or any other day of the week, even)? The principle of it is this: grab some of the focused searches out there that land on this site (i.e Flickerdown) and attempt to respond to them with more data. Deal? Let’s begin, then.

Search Term #1: ax4 iops

No really good answer to this but I will attempt one anyway. You cannot derive a raw IOP count from an AX4-5 simply because it’s going to be based on several factors:

  • Spindle Speed
  • Drive Type (really predicated by the spindle speed)

So, understanding this, I use the following breakdown to determine RAW IOP counts across all drive types (fibre, SAS, and SATA):

  • 15,000 RPM drives: 170-180 IOPS
  • 10,000 RPM drives: 120-130 IOPS
  • 7,200 RPM drives: 80-90 IOPS

Underlying this also is the type of RAID group sitting on top of these spindles. RAID 10, RAID 5, RAID 3, RAID 1, etc. will have an impact on the I/O streaming to/from the array and will impact your overall IOPs count.

Make sense? 😉

Search Term #2: how does a celerra work?

This is a GREAT search term and I’ll try to keep the fluff to the minimum on this one. Essentially, our Celerra operates on a few different methods of communication: NAS, iSCSI (IP-based block transfer), and Fibre.

  • NAS: NAS functionality takes the form of two primary protocols: CIFS and NFS. The Celerra can emulate or virtualize NFS (v2, v3, and iirc, v4) as well as CIFS (i.e. Microsoft file systems). Especially keen if you’re in a Microsoft Windows Active Directory environment is the ability to virtualize baseline file server functions onboard the Celerra. Essentially, you create a virtual Windows 2003 file server within the Celerra (no license from Microsoft needed!) and to your end users, it looks just like another file share. You can have the users bound to it through startup scripts, etc. and created a managed storage strategy.
  • iSCSI: iSCSI is supported from an intiator/target standpoint and is supported from a hardware (TOE card) or software (i.e. host-based software) standpoint. Again, the Microsoft side of the house benefits from an actually decent software initiator that offsets the need for any sort of TOE card to begin with. On the Open Systems side, these software initiators are getting much better with communities like developing solid driver sets for use by the general public.
  • Fibre: Fibre is supported in either direct connect (host to array) or switched (host to switch to array) topologies. Similar to our Clariion line of storage arrays, you can zone hosts to a particular LUN set, create RAID groups and LUNs on the fly, etc. etc. etc.
  • Other Protocols: This probably falls under the NAS functionality, but I thought I’d break this out here. Along with virtualizing CIFS or NFS shares, you can also emulate FTP and HTTP services within the array.

The Celerra has evolved from being an IP-only box to being truly the multiprotocol platform SMB and Commercial companies need. Very cool technology. 😉

Search Term #3: ax4 compared to cx3-10

Since I’m asked this question a lot, I figured I’d rather answer it on my own terms. That being said, there are a few distinct areas of difference:


  • Intermixed SATA and SAS drives within the same DAE (Disk Array Enclosure)
  • SAS drives
  • 12 drive DAEs
  • iSCSI or Fibre Channel only (no combo)
  • 4 port fibre or iSCSI physical interfaces
  • Navisphere Express management interface with Navisphere Manager optional
  • Limited array replication technologies
  • RAID Group type limited to: RAID 1 (RAID 1/0 in a 2 disk set), RAID 3, or RAID 5


  • Separated SATA and Fibre DAEs
  • Fibre drives (vs. SAS)
  • 15 drive DAEs
  • iSCSI and Fibre connectivity (Combo units only)
  • Navisphere Manager management interface
  • More robust array replication options
  • RAID 6 support

Cost is also different between the two but that’s for the sales team to dink around with.

Closing Thoughts

Anyhow, that’s all for today! Will hopefully see you next week with some more search term explanations!


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