Stephan_84

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  1. Stephan_84

    MSSQL - SSDs vs. HDDs

    Hello Kevin, thanks for your help. The model mentioned above does not have limited warranty. If the SSD (read-intensive) will fail, the drive will be replaced by DELL. Its not bulk read activity, the Workload is OLTP. Current workload: Database traffic: 50% 64k read, 50% 64k write T-Log traffic: 100% 4k write Overall: 75% write (4k-64k), 25% read (64k) I did a quick IOPs calculation based on this workload (not paying attention to the IO size, 140 IOPs each HDD): 18 x HDD - Raid 10 75% write, 25% read Max. write IOPS: (Raid 10 write penalty: 2): (140*18)/2 = 1.260 IOPs Max. total IOPs with 75% write, 25% read: (0,75*140*18)/2 + 0,25*140*18 = 945 + 630 = 1.575 IOPs 4 x SSD - Raid 5 75% write, 25% read Max. write IOPS: (Raid 5 write penalty: 4): (4000*4)/4 = 4.000 IOPs Max. total IOPs with 75% write, 25% read: (0,75*4.000*4)/4 + 0,25*78.000 = 3.000 + 19.500 = 22500 IOPs If this calculation is correct, the read-intensive SSD type should me much faster, even on 100% write workload, right? I am still anxious buying a type of SSD witch is labeled with "read-intensive", for my 75% write database workload. Is this something I should be worried about? Are 4 SSDs, based on the caluculation above, really that much faster? Thanks in advance, Stephan
  2. Stephan_84

    MSSQL - SSDs vs. HDDs

    Hello Kevin, thanks for your help! What exactly is the disadvantage? Is it sequential write speed only? Typical OLTP Workload should be faster even with the read-intensive model, right? I am not able to buy individual components, because I need full Dell Support. Thanks in advance, Stephan
  3. Stephan_84

    MSSQL - SSDs vs. HDDs

    Hello Brian, I tried to keep the question simple, here are some more facts: There will be two bare metal server with identical configuration. Operating System will be Server 2012 R2, SQL Version will be 2014, configured as always on availability groups. We need to buy the servers directly from Dell, but we will do the installation and configuration. Current database size is ~600GB (DB files and tlogs). Growth rate is 180GB each year. Our performance calculation is based on the current servers with 8 x 300GB 10k HDDs. There are no performance bottlenecks at the moment. We used the database growth rate as a metric to scale up the IOPs from 8 disks to 18 disks. We assume that the “Option 1” would successful handle our performance requirements. Workload is OLTP. The question: is the “Option 2” with SSDs faster/better/suitable? Is there a problem using “Read Intensive” SSDs on a Database Server, or is this type of SSD still much faster than 18 HDDs? As mentioned the Options are nearly the same price. Thanks in advance, Stephan
  4. Stephan_84

    MSSQL - SSDs vs. HDDs

    Hi there, I need some advice or maybe another opinion regarding a MS SQL Server disk configuration. Requirements Dell Server 2TB usable disk space No limited Warranty SSDs (Need more than 3yr Support) Only Dell the SSD Modell “read intensive SSD” (SAS 6G, MLC) is cheap enough, to fit into our budget Perc H710p Raid controller These are the two current configuration Options. They are sold at nearly the same price. Options 1 18 x 10k 300GB HDD Raid10 (maybe two separate raid sets) Option 2 4 x 800GB read intensive SSD Raid5 SSD Specs 4.000 IOPS 4k Random Write 17.000 IOPS 8k Random Write 78.000 IOPS Random Read 140 MB/s Sequential Write 310 MB/s Sequential Read Witch Option would you prefer? And why? Thanks in advance, Stephan