In our company we're using Hyper-V (Windows Server 2012) hypervisor and VM to organize our in-company services in our data-center. I am supposed to set up Ubuntu 12.04 LTS guest for our main database (Postgresql).
My sysadmins gave me a SSH connections do VM (Ubuntu is already there). Disks are dynamically resizeable VHDX files.
XFS file system has a lot of creation and mounting options. I've read lots of material about XFS possibilities but they're basically so-called bare-metal guidelines (depending on RAID and disks parameters and physical layout). I don't really know which one are relevant in my case. Especially two things bothers me:
- Does partition alignment matters in VM environment? Should I ask my sysadmins about physical RAID parameters (disk count, stripe size)? And set my XFS according to them?
- Allocation Groups (AG) and xfs parallel I/O feature. As far as I understand the concept: we divide file-system in parts and FS could try to perform let's say two writes in parallel if they're going into two different AGs. Could I really achieve this with dynamically resizable VHDXs since it's not physical device with real space to divide?
Because of virtualization it's really cloud computing in my point of view. I don't have any guarantee where VHDXs reside and how long there will be there (it's my hypervisor admins job). So maybe I'm looking totally at wrong issues as far as setting storage for DB in Hyper-V environment is concerned? If so, could you please recommend me topics that I should check out
Best Answer
I understand that your backing storage may change and you may not have knowledge of the underlying hardware. The following is pretty safe for me in virtualized environments:
Today, my XFS creation and mount options look like:
Where "sdX" is the device name. That's a 256 Megabyte log and a 4k sector size.
Mount options are typically:
Those are no access-time, no write barriers, and modified log buffer/block sizes.
Using a modern OS, make sure that your partitions are aligned. Using
fdisk
, change your display units to sectors. Heed the warning:A properly aligned partition under RHEL6: