Search Term Tuesday – June 3rd Edition

by dave on June 3, 2008

Note: I’m trying to tighten up the layout of content on the landing page, so, I’ll be using excerpts more and more.

Continuing from last week, this edition of Search Term Tuesday will tackle the most important searches (or at least highest ranked statistically) that landed you at this blog.

Search Term #1: cx3-10 create raid group

Rather than delve in too deep here, I thought I’d point you to this excellent video regarding LUN Expansion (and as a pre-requisite, RAID Group creation) done by Wendy Bertino.

Navisphere Manager LUN Expansion Demo

Enjoy and let me know your feedback.

Search Term #2: emc cx3-20 expand raid group (takes days)

This particular search obviously points to an issue with the array and production. Let me highlight a few reasons why a RAID group expansion might take days.

Depending on what type of RAID group you’re expanding (I’m going to assume RAID 5), there are couple of things that need to happen.

First, you’ve got to re-calculate the parity of the RAID set across additional member disk(s). Adding 2 disks to a 5 disk RAID 5 set means that the entire parity stripe has to be recalculated. This is true for Equallogic, NetApp, EMC, IBM, HDS, HP etc.

Secondly, the entire data stripes or LUN stripes have to be re-spread across the additional spindles. In systems like Equallogic, you literally will have to restripe across 16 disks at a time which is not an efficient use of the production system. In the EMC world, you would have to restripe data + parity across the member disks only while the rebuild is happening.

Finally, The other variable is how many blocks of data you have present. A 500Gb rebuild will take less than a 5Tb rebuild (for obvious reasons). If you’re continually in production while this expansion is occurring you’ll continually be extending your rebuild window based on the influx of new data to the array (which is why we typically recommend doing this off-peak or using another method of expansion like LUN migrations or MetaLUNs).

Hopefully that helps with a more technical explanation.

Search Term #3: renderboxes

So, this has absolutely nothing to do with EMC (or does it? LOL!) but does have more to do with what I LOVE doing as a hobby: building CG workstations or renderboxes. Nothing makes me happier that putting together high performance hardware that will get hammered by the end users software and work 24/7. So, yes, I build renderboxes in my basement, during my spare time. Feel free to email me if you have any questions about architecture, technologies, etc.

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