SQL Server Performance

ML370/P400 - more than 8 drives in one array?

Discussion in 'SQL Server 2005 Performance Tuning for Hardware' started by daviobrien, Mar 13, 2007.

  1. daviobrien New Member

    Based on the posts in this forum, we ordered several of the new ML370s and are trying to configure them properly.

    We have 16 SAS SFF drives, the second drive cage, and a second P400 controller. I need to create a single array across 12 drives.

    Currently, each controller card has two ports. Each port is connected to one half of the drive cage. In the array manager, each controller only has access to 8 drives.

    My system guys and our VAR said 8 is the max for the controller but the spec page for the P400 indicates that it can connect to a maximum of 18 drives:

    Any ideas?
    Is there a way to jumper the cages so that one connection controls all 8 drives?
    Is there some type of expander cabling from HP that will allow this controller to connect to 18 drives?

    I appreciate any help you may have.

  2. joechang New Member

    HP Smart Array controllers should let you put as many drives as you can connect in one array
    or alteast 56 for their RAID 6 ADG
    they recommend max of 14 for RAID 5

    of course, this means actually connecting 12 or 16 to one controller
    it sounds like you connected each drive bay to its own controller
    which means there 8 drives per controller

    depending on whether you have 1 P400/i and 1 P400, or 2 P400
    the 400/i can only connect to 6

    if you do connect both bays to one P400, you lose the benefits of dual controllers

    personally, I recommend distributing disks across multiple controllers
    and this implies splitting a db across multiple files
  3. daviobrien New Member

    Thanks Joe. I'll plan on splitting the array across the two controllers.

    It looks like the P400 supports 18 drives, but you need to have the ML570 to do so. It has one cage that holds 18 drives and connects to the controller with a single cable. The cage must have some type of expander chip inside.

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