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Re: [Xen-API] Block Alignment - Any XCP guidance?


  • To: xen-api@xxxxxxxxxxxxx
  • From: George Shuklin <george.shuklin@xxxxxxxxx>
  • Date: Sun, 25 Nov 2012 17:55:39 +0400
  • Delivery-date: Sun, 25 Nov 2012 13:56:02 +0000
  • List-id: User and development list for XCP and XAPI <xen-api.lists.xen.org>

I see no correlation between "netapp optimization" and local ext3 storage, really.

If you using LVM/NFS, all data will be aligned. VHD format use bitmap headers before every 2Mb of data, it takes about 512 bytes, but other 1488 are simply skipped, so data will align 4k boundary.


On 25.11.2012 17:40, Jonathon Royle wrote:

At work I am having lots of discussion on block alignment with NetApp. As I read various forums there is lots of advice on checking/fixing block alignment however it appears to be very VMware focused. I note Win 2008 R2 and Centos 6 automatically start partitions at 4k block boundaries but Centos 5 does not.Â

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So my key Q is â as XCP uses Centos 5 as Dom0 and is therefore not block aligned is there a performance hit in using local ext3 storage repositories (my reading suggest LVM SRs should not be impacted)? If yes is there a way to avoid/correct this?Â

Â

Regards,

Â

Jon

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