Posts by CristieStorageMonkey

Facebook Frankenphoto morgue will store your cold, dead selfies FOREVER

With 1,382,400TB of raw storage, assuming a maximum of 2 drives is active per device tray gives us 92,160TB of actual, raw storage at any one time. If we then assume that the ratio of original:copy data is 1:2 (for availability), we have 30,720TB of usable storage at any one time.

30PB is still an incredible figure, considering that there are potentially 15 multiples of this (totalling ~460PB) of disk storage from that all-disk datacentre.

I don't know how the data placement algorithms work, but it would seem most logical if the relative objects are collated and spread across one particular lot of drives, unless these drives are themselves broken down into logical groups which may be necessary, given the sheer number of drives that could be active at any one time (23,040 drives in total x 4TB = 92,160TB). Drive groups could then be spun up and spun down based on user activity, for instance, one individual flicking through photos in various albums they own or are tagged in.

Re: Assuming they use 4TB SMR drives: 4 x 345,600 = 1,382,400TB

It's *highly* unlikely Facebook use RAID practices for the bulk of user data....

You don't. Well, not really. You just ensure availability of that data, and leave as high a proportion of errors down to individual users. And often, when they're not paying, any user error is their fault and they shouldn't have been so silly.

Re: I'd love to see is the

[Disclaimer: Given this is written text, I'm not sure whether or not your comment was in jest...]

} If not, that would - quite frankly - never hapen due to the way Facebook (and almost all big data houses) architect their platforms. Availability of individual components, or their lack of due to failures (be it drives or servers), do not adversely impact the availability of others. Gone are the days of traditional RAID, for example, for these guys.

} If so, [chuckles] :-)