Re: BBU still needed with SSD?

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On 2011-07-19 13:37, Florian Weimer wrote:
Is this "Total_LBAs_Written"?
I got the same name "Total_LBAs_Written" on an 5.39 smartmontools, which was renamed to 241 Lifetime_Writes_GiB after upgrade to 5.42. Note that this is smartmontools new interpretation of the values, which happen to match with the OCZ tools interpretation (241: SSD Lifetime writes from host Number of bytes written to SSD: 448 G). So for the Intels it's probably also lifetime writes in GB but you'd have to check with an Intel smart values reader to be absolutely sure.
   The values appear to be far too low:

241 Total_LBAs_Written      0x0032   100   100   000    Old_age   Always       -       188276
242 Total_LBAs_Read         0x0032   100   100   000    Old_age   Always       -       116800

241 Total_LBAs_Written      0x0032   100   100   000    Old_age   Always       -       189677
242 Total_LBAs_Read         0x0032   100   100   000    Old_age   Always       -       92509
Hmm that would mean 188TB written. Does that value seem right to your use case? If you'd write 100MB/s sustained, it would take 22 days to reach 188TB.
The second set of numbers are from the drive which wears more quickly.
It's strange that there's such a large difference in lifetime left, when lifetime writes are so similar. Maybe there are more small md metadata updates on the second disk, but without digging into md's internals it's impossible to say anything constructive about it.

Off-topic: new cool tool in smartmontools-5.4x: /usr/sbin/update-smart-drivedb :-)

--

Yeb Havinga
http://www.mgrid.net/
Mastering Medical Data


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