Does the availability of SSDs affect the desirability of quantity of disks vs. size, Christof?
-- rk -----Original Message----- From: ProfoxTech [mailto:[email protected]] On Behalf Of Christof Wollenhaupt Sent: Wednesday, June 19, 2013 4:33 AM To: [email protected] Subject: Re: [NF] Intel i5 vs. Xeon CPU for a data server CPU usage isn't a valid measurement to compare desktop and server CPUs. The same application might use 5% on a Core i5, but only 2% on a Xeon E7 due to triple the cache, better conflict management, better predictive queues, etc. A Xeon would still be twice as fast in this case. A core isn't a separate CPU. A number of parts of the CPU do not exist once per core and are shared among cores. Most importantly, the cache and the bus are shared. Before you do any guessing, you could rent a server in a data center for a month and do some load testing yourself. Amazon rents Xeon machines by the hour for a few cents per hour. In a data center you get a i5 for less than $100 a month and Xeon for less than $200. With a database server I'd pay probably pay more attention to storage, memory and connectivity. Instead of local storage, I'd probably get a SAN connected via multipath GB network. There're inexpensive SANs available from Qnap, Synology, and the like. Most of them offer replication between two instances. If the database server performs replication, that's extra load and bandwidth taken from read-only, in memory queries that the server could do instead. If your database application has lots of writes you have to pay attention to IOPS on the storage system. 200 clients on a single mirrored disk system with 150 IOPS means that a write operation will take about a second. Replace it with a RAID that has many spindles, you increase IOPS linearly. IOPS are the reason that most server disks are still small (600 GB, 1.2 TB), because in a server you want more disks, nor larger disks. Closely related is the topic of alignment. In a database server the database block size MUST align with the cluster block size and location of file systems and disk. Otherwise you might end up with a system that has to read/write multiple clusters for every database block. That's especially important as some file systems use significantly larger cluster sizes of up to 2 MB or with virtualized drives. When you test network performance keep in mind that bandwidth is only part of the equations. The other important measure is packets per second (PPS). Every switch/router/hub has a limit of how many IP packets it can manage per second. Higher PPS values are often the reason that a business switch is so much more expensive than a consumer device even if both have GB ports. -- Christof _______________________________________________ Post Messages to: [email protected] Subscription Maintenance: http://mail.leafe.com/mailman/listinfo/profox OT-free version of this list: http://mail.leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/DF1EEF11E586A64FB54A97F22A8BD0442280DDBC69@ACKBWDDQH1.artfact.local ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
