Quoting Amos Shapira, from the post of Thu, 22 Feb: > > Yes but these were all practically identical disks - Guy's response was > about my idea to mirror a RAM disk with a regular magnetic media disk, which > would mean that that this volume will be as slow as the magnetic media, so > loosing the advantage of investing in a RAM disk.
an OS-level RAID like that would certainly lose all benefits of the speed of writing (transactions would not be final until the disk informs you it fnished writing), but your reading will be nice and fast. however, that's less usefull than any DBMS caching tables and queries in memory... the one mechanism that does what you are describing is the MySQL "NDB" backend, also known as MySQL cluster, where all the DBs' tables are in the RAM of the participating nodes, and commiting to disks is done rarely and not even by all the nodes if you don't want it to. the collection of RAM of all the machines is your RAID in a way, and the speed of transactions is said to be phenomenal in theory because you never use the disks, you just trust your UPS very very very much. In practice however, I understand it's not a major speed boost, some say, but I never tested it myself, and I have no idea why. -- Japanese Seizure Robot Ira Abramov http://ira.abramov.org/email/ ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
