Ok Marc. Sounds like you have experience there.. could you share how slow it is? Thanks.
Best, Peter -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Friday, September 28, 2007 5:01 PM To: Peter Chiu Cc: Mdecandia; [email protected] Subject: Re: Fault Tolerance? You would be surprised how *SLOW* it is to fetch even the most simplest objects from NDB. This has to do with the way mysql-cluster is designed and cannot be overcome so easily. Forget about using NDB as a cache. Peter Chiu wrote: > Totally agreed. What about building a HA memory cache based on NDB, running > on machines with plenty of RAM (64GB)? That way NDB would cache most of the > stuff in memory for fast access, while at the same time provide HA. Ideas? > > Best, > Peter > > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mdecandia > Sent: Friday, September 28, 2007 3:50 PM > To: [email protected] > Subject: Re: Fault Tolerance? > > > On Sep 27, 2007, at 22:16, Dustin Sallings write: > >> On Sep 27, 2007, at 21:56, Paul Scott wrote: >> >> >>>> Agreed. Wouldn’t it be great though to have a mem-based HA datastore? >>>> >>> I would certainly vote +1 on that idea! >>> >> You do realize you wouldn't have anything remotely like the >> performance of memcached, don't you? You'd need something along the >> lines of two-phase-commit if you want any kind of correctness. If >> you don't want correctness, then why are you worried about HA? >> >> > We use memcached to store items fetched from a slow service, not from > database. > Performance difference between this service and memcached are huge. > May be really convenient to have an HA feature on memcached servers. > > >> If you lose a node, how do you plan on rematerializing? A complete >> synchronization would block both nodes in a two-node cluster. >> > > We've introduced libketama consistant hashing to reduce effects on server > faults but > it will be useful to have a redundant caching system between servers to be > really fault toulerant. > > >> How would you handle conflicts during rematerialization after a >> netsplit? >> >> Is it acceptable to block all clients during a netsplit (pending >> some sort of magical synchronization that knows what to do when >> conflicts occur)? >> >> After you get all of the pieces in place, are you sure you'd have >> something that would be any faster than any solution that isn't >> completely in-memory? >> >> -- >> Dustin Sallings >> > > Michele > > > -- > Email.it, the professional e-mail, gratis per te: http://www.email.it/f > > Sponsor: > Problemi di Liquidità? Con Logos Finanziaria 30.000 € in 24 ore a > dipendenti e lavoratori autonomi con rimborsi fino a 120 mesi clicca qui > > Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=2907&d=20070928 > > >
