Inside System Storage -- by Tony Pearson

Tony Pearson Tony Pearson is a Master Inventor and Senior IT Specialist for the IBM System Storage product line at the IBM Executive Briefing Center in Tucson Arizona, and featured contributor to IBM's developerWorks. In 2011, Tony celebrated his 25th year anniversary with IBM Storage on the same day as the IBM's Centennial. He is author of the Inside System Storage series of books. This blog is for the open exchange of ideas relating to storage and storage networking hardware, software and services. You can also follow him on Twitter @az990tony.
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Comments (5)

1 localhost commented Trackback

My apologies. Post corrected.<div>&nbsp;</div> If you had sent me an email about the earlier inaccuracy on my blog - I would have happily corrected it.<div>&nbsp;</div>

2 localhost commented Permalink

TonyBananas don't have opposable thumbs but I'm pretty sure chimps do.Peeling those bananas would be tough without them!<div>&nbsp;</div> Keep up the good work!<div>&nbsp;</div> RegardsRob Clare, IBM UK

3 localhost commented Trackback

One question I did have relates to rebuild times. A single disk can be rebuilt in 30 minutes, but what if a node gets a bad memory stick or a motherboard failure? How long does it take to rebuild all the drives in that node? How much impact does this rebuild have on production? Also, I've heard two numbers regarding the usable and raw space. Could you clarify whether it's 80/120, or 80/160? Also, how many disks can be lost before there's a risk of data loss? <div>&nbsp;</div> Thanks!

4 localhost commented Trackback

Robert,Good catch! Of all the animals I could have chosen for the analogy, I picked one that actually DOES have opposable thumbs like humans do. Mea culpa. I have corrected the post above.--- Tony

5 localhost commented Trackback

OSSG,This sounds like more than one question! The worst case scenario for 1TB drives is 30 minutes, but typical times found by our clients is in the 3-10 minute range. That said, losing a drawer of 12 drives is theoretically 12x longer, so 1-6 hours, depending on the amount of data written, and the amount of activity for production I/O.<div>&nbsp;</div> Whether you lose a single drive or all drives in a drawer, you are reading evenly across 168 drives. The impact has been measured to be about 1 percent performance degradation during the rebuild process.<div>&nbsp;</div> If you do not have synchronous mirroring set, you can lose up to 12 drives on a single drawer before data loss. With synchronous mirroring, you can potentially lose more drives before data loss.<div>&nbsp;</div> The usable TB in the IBM XIV Storage System is 79TB. This is a huge increase over the 51TB usable in the previous generation. Capacity on Demand pricing options allow you to get initially as little as 21TB with options to use more space as needed over time.<div>&nbsp;</div> -- Tony

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