I read that Vertical Scaling reduces the Reability ... how it can ? Is replacing processor for example from 1 Ghz to 2 Ghz is also vertical scaling ? or Vertical scaling just mean by "adding" not "replacing" processor and memory.. I know that by adding new processor then the reability is reduced a bit.. because we have more probability of fail caused by new added processor (if one fail, then all of them are fail). Thx, Amin
Yeah I don't understand also very well.. Vertical: Achieved by adding capacity (memory, CPUs, etc.) to existing servers. Requires few to no changes to the architecture of a system. Increases: Capacity, Manageability Decreases: Reliability, Availability How can it reduce reliability and availability, in my opinion, it remains the same... Gus Dur
My $0.02 In that statement, the author does not really imply that VS will reduce Reliability / Scalability, perhaps the way to read it would be that VS will have little / no impact on Reliability and Availability, as compared with HS. VS, as has been pointed out is achieved by adding processors / memory ...as opposed to HS, where new servers are added. If you have just changed your server from a 2 processor m/c to a 4 processor m/c, how does that change availability / reliability? In multi-processor systems, the underlying OS is intelligent enough to spread its processing load amongst the processors. However if the disk array crashes, what difference will it make whether there were 2 or 4 processors? None. The m/c is down. Does both reliability and availability threats still exist even after VS. As opposed to VS, in HS, new machines are added. You also either have specialized applications that can manage load or your software supports some kind of clustering and redundacy. In this example, if one server fails, the redundancy machanism will kick off and the system will continue to be available. Thus HS actually enhances the Reliability / Availability of a system. HTH.
Sanjay Raghavan<br />SCJP2, SCEA-J2EE<br />Moderator - <a href="http://groups.yahoo.com/group/scea_prep" target="_blank" rel="nofollow">SCEA PREP</a><br />Co-Author - <a href="http://www.whizlabs.com/scea/scea.html" target="_blank" rel="nofollow">SCEA@Whiz</a><br /><i>Where did you sip your Java Today?</i>
Oh, sure, you could do that. Or you could eat some pie. While reading this tiny ad: