ESXi

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  • 1.  Raid 5 and Number of Drives

    Posted Sep 06, 2013 02:03 PM

    I am setting up new servers and I was reading the release notes on the 5.1 U1 and it gave examples of supported raid.

    I was planning on installing 8 1TB drives and setting them up RAID 5.  The release notes says that they support the following examples.  It says 7 1TB drives in that note.

    Is this just an example or if I use 8 drives will my server explode?  It just seems weird that I can use 7 but not 8 rather than a set rule of max number drives in a particular RAID type statement.

    Anyone have any insight into this or do I have to burn a support call.




  • 2.  RE: Raid 5 and Number of Drives

    Posted Sep 06, 2013 02:53 PM

    It has to do with the SCSI addressing - depending on the SCSI bus because some only have 8 addresses available - one is taken by the SCSI card leaving 7 available for drives - from Google -

    On SCSI parallel buses the number of ids is related to the width. 8 bit buses (sometimes called "narrow") can have 8 SCSI ids of which 1 is taken by the HBA leaving 7 for SCSI devices. Wide SCSI buses are 16 bits wide and can have a maximum of 15 SCSI devices (targets) attached. The SCSI 3 draft standard allows a large number of ids to be present on a SCSI bus.



  • 3.  RE: Raid 5 and Number of Drives

    Posted Sep 06, 2013 03:34 PM

    Thank you very much.  You know that actually makes sense.  So no big deal I guess I will go with the 7 as opposed to 8.  Do you have any opinion on the RAID type.  I have seen so many different opinions about raid 5 vs raid 6 vs raid 10.



  • 4.  RE: Raid 5 and Number of Drives

    Posted Sep 06, 2013 08:49 PM

    It really depends on what's going on the drives. Will there be a SAN?



  • 5.  RE: Raid 5 and Number of Drives

    Posted Sep 06, 2013 08:57 PM

    It is local storage.  Can't afford SAN.  We have 2 drives Raid 1 for ESXi.

    Then 8 1TB drives for data on each server.  We plan to use the Storage appliance.  The VMs are standard Windows 8 R2 running Exchange 2010 and print and file sharing, and SharePoint.

    I have seen that there is better performance on the raid 10 so I might go that way but the HP servers need additional license to get that option.

    Thanks for your help.




  • 6.  RE: Raid 5 and Number of Drives

    Posted Sep 06, 2013 09:12 PM

    I would go RAID 5 - provides decent performance for most applications -

    Also with you SCSI are able to enable the Wide SCSI bus this will allow you to use all 8 drives -



  • 7.  RE: Raid 5 and Number of Drives

    Posted Sep 06, 2013 09:22 PM

    Thanks.  I am just so afraid of setting this up and it not performing well.




  • 8.  RE: Raid 5 and Number of Drives

    Posted Sep 06, 2013 09:41 PM

    Performance anxiety??



  • 9.  RE: Raid 5 and Number of Drives

    Posted Sep 09, 2013 05:37 PM

    Ha funny!




  • 10.  RE: Raid 5 and Number of Drives

    Posted Sep 09, 2013 11:40 PM

    Poorly performing RAID is nearly always the result of a cheap RAID card, the lack of a battery backed cache, or too small a cache.

    These issues have exponentially more impact than the RAID level.

    Edit:

    I have seen that there is better performance on the raid 10 so I might go that way but the HP servers need additional license to get that option.

    This is not a licensed feature and you can choose to do so. However, if you require performance at a high enough level that you need to go down this path, the Storage Appliance is unlikely to be usable to you.