Messages in this thread | | | Date | Sat, 15 Mar 2008 21:03:08 +0000 | From | Alan Cox <> | Subject | Re: [ANNOUNCE] Ramback: faster than a speeding bullet |
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> > RAID controllers do not have half a terabyte of RAM. > > And? Either you have battery backed ram with critical data in it or > you do not. Exactly how much makes little difference to the question.
It makes a lot of difference, and in addition raid controllers (good ones) respect barrier ordering in their RAM cache so they'll take tags or similar interfaces and honour them.
> That is why I keep recommending that a ramback setup be replicated or > mirrored, which people in this thread keep glossing over. When > replicated or mirrored, you still get the microsecond-level transaction > times, and you get the safety too.
Either you keep a mirror in sync and get normal data rates or you keep the mirror out of sync and then you need to sort your writeback process out to preserve ordering.
If you want ramback to be taken seriously then that is the interesting problem to solve and clearly has multiple solutions if you would start to take an objective look at your work.
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