5 ms·
I take it you only read the first part of the article. They used RAID6 over 15 drives each, combining those 15 drives via LVM, allowing the loss of 2 drives fr
by soult 15y ago
I take it you only read the first part of the article.
They used RAID6 over 15 drives each, combining those 15 drives via LVM, allowing the loss of 2 drives from the same group without data loss. This is the same configuration Backblaze uses as well, because even though their fancy custom software mirrors all data to different storage pods, it is easier to just replace a drive and rebuild the raid than rebuilding the whole JBOD from the data on other pods.
- nobody314159 15y agoThe problem is that a large number of the failures that would take out 2 of 15 drives in a raid array will also take out all 15! Think bad power supply, mains spike, cooling failure, fire, flood ..... If you need raid, you also need a separate copy in a separate location.
- nknight 15y agoYour point isn't entirely invalid, but I lose HDDs a hell of a lot more often than I encounter any of the other problems you mention. I don't think I've seen a power supply pop since 2006, I've never lost UPS/surge-protected gear to a mains spike, every server room or datacenter I've cared about has been environmentally monitored, heptafluoropropane exists for a reason, and why are you building a datacenter on a floodplain? In contrast, I lose 5-10% of the spinning HDDs I care about every year.
- trin_ 15y agojust curious but do you have any data for SSD in use?
- nknight 15y agoNo, I've not dealt with enough of them for long enough to have anything meaningful to say on the subject. So far I've not even had one clearly die (though there have been some very odd transient incidents.) Jeff Atwood made an interesting post on that very subject a while back, though: http://www.codinghorror.com/blog/2011/05/the-hot-crazy-solid-state-drive-scale.html http://www.codinghorror.com/blog/2011/05/the-hot-crazy-solid...
- VikingCoder 15y agowhy are you building a datacenter on a floodplain? Every spot in our solar system is susceptible to some unrecoverable disaster. If you don't want to lose your data, you have to have copies in more than one physical location.
- nknight 15y agoYeah, I'll get right on that Mars mirror. Seriously, I didn't say he was wrong in theory, but focusing so much attention on the highly unlikely to the detriment of the exceedingly common is a drastic distortion of the issue, and a cost/benefit analysis skewed in either direction can have costly repercussions.