Spanned Volume Performance

Question

_{Wednesday, November 24, 2010 9:49 PM}

I am planning a large file server implementation.  My plan is to create 4 volumes that are 2TB large and expand those volumes in the future by spanning the disks.   

Here are some technical details.  All disks will be connected to the same RAID controller.  There will be 2 RAID5 Disk Groups.  Each Disk group will have 4x2TB LUNS that are presented to the host.  These 2TB LUNS will then span the original 2TB LUNS.  

When considering spanning the disks, another layer is added into the mix.  Will there be a performance loss when spanning disks?  Is there anything else I need to consider?

Thanks!

All replies (3)

_{Wednesday, November 24, 2010 10:08 PM ✅Answered}

Disk spanning does not change anything about performance.

Consider decreased reliability level - in case if single piece of span fails, the whole span is lost. Well, it' s not an issue when playing with RAID; but previously, I saw some spans that were lost because of logical (filesystem?) errors.

MCITP: Enterprise Administrator; MCT; Microsoft Security Trusted Advisor

_{Wednesday, November 24, 2010 10:58 PM}

Interesting that a file system error could create this.  Sounds like if it's a file system error it could still be the case if both disks were raided, is that true?

_{Wednesday, November 24, 2010 11:36 PM}

To create a spanned volume, you need both disks to be converted to dynamic. In my case, it was like after the usual shutdown/restart the system has lost one of the dynamic disks and then found a new one! Of course, the span was lost.

I got this by myself on two different systems and I'm pretty sure I was not tampering with disks; neither any system-related software was installed and running.

MCITP: Enterprise Administrator; MCT; Microsoft Security Trusted Advisor