Sunday, September 16, 2012

When vendors start making up terminology

I recently had to call Dell, because we had one drive fail and then three others go into "predictive failure" mode during the rebuild on a PowerVault MD1000. The 14 disks were in RAID 5 with two hotspares (this predates me, put your nooses and torches away. The box now runs RAID 6 with 1 hot spare).

While Dell was doing their normal routine diagnostics before shipping out 4 disks to me, they informed me that my array had a "punctured stripe." Punctured stripe? What the heck is that, I asked? They proceeded to explain how RAID 5 works with striping and parity, which I already knew. Then they said that in large volumes sometimes during a rebuild the stripe punctures because of inconsistent parity data and the whole volume needs to be completely re-initialized and restored from backup. "Oh, so you mean it's a URE?" "A what?" "An unrecoverable read error during the rebuild." "Um, I guess?"

The Dell storage "engineer" had never heard of a URE - which is an industry standard term! Upon further googling, it seems that Dell support is really the only company that uses this term. I had to make two follow up calls and got two different engineers and every single one said "punctured stripe." If there is an industry standard term for something, please don't try and coin a new phrase! It confuses your customers and makes us think that your storage engineers are clueless, because they don't know them.

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