SQL Server Performance

How much Ram do we need for SQL 2K5

Discussion in 'SQL Server 2005 Performance Tuning for Hardware' started by WingSzeto, Dec 4, 2007.

  1. WingSzeto Member

    We are going to upgrade W2K3 to W2K3 entreprise version on a new server and use SQL 2K5 standard version with sp2. Our current server which has 4 Gbytes of Ram and using W2k3 server standard edition and our transactional database's size is about 30 Gytes. Our Buffer cache hit ratio is consistently 99% and Lazy writes/sec is 85% of time stay under 5. The max sometimes could be over 50 but it doesn't happen often. Our IO doesn't have much bottleneck and if it happens, it usually is because of some unusual queries which sometimes I can track down and fix.
    Based on the above info, I would like to add more RAM's just to handle some unusual circumstances. I read some blob but I didn't get a good feel on how I should determine how much RAM I would need based on what I have stated here. Here are my questins.
    1) Is there a good way to find out how much RAM we need in relation to the database size? I am just looking for some common sense approach.
    2) Is more RAM always better even though the server is performing quite well (based on the info I provide above)? If I have a 30 Gbyte db, If I put in 32 Gbytes of Ram, technically the entire db can be housed in there. I know SQL 2K5 won't do it that way but in my mind, more RAM means it would allow more buffers for SQL 2K5 to manage and in turn it should be better for our performance. Based on this thought, even thought I think 16 Gbytes should be more than enough, I am thinking putting in 32 Gbyes since memory is cheap nowadays. Am I thinking this right? Am I wasting money because the gain in performance from 16 G to 32 G will be not much.
    Any advice on this would be very much appreicated.
  2. Luis Martin Moderator

    If you already have good performance with 4GB with 30Gb database, you have to think about database growing in the future. So, 16GB sound good to me in this case.

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