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I am creating backup volume on RAID6 and I want to expand it in the future up to 12 2TB discs. Currently we have 4 discs in RAID5 and 4096 allocation unit + file compression on. Everything is working great.

Now I am creating the new volume (today just for testing) and I am wondering if I can set up same parameters when formatting it, do not want to get stuck after adding 6th disc because the allocation unit or the compression will not be supported on bigger size and I will not be able to extend the volume after adding new discs to the array.

Thx for all help in advance.

Windows 7 on virtual machine hosted by Hyper-V 2008R2 with 'virtual SCSI' access to disc on PERC 6e / MD100 of main box.

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up vote 7 down vote accepted

You cannot have a 20 TB volume with compression, due to the maximum allocation unit size for those two features is 4,096 bytes.

With that allocation unit size, the maximum NTFS volume size is 16 TB.

This is because NTFS is limited to 2^32 -1 clusters.

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The answer is correct with regard to compression, but not with regard to EFS encryption. I'm on Windows 7 SP1 64-bit and can encrypt a folder just fine on a drive with 16kb allocation unit / cluster size. Here's the proof: (and here's a backup link in case that one goes down – rkagerer Aug 11 '15 at 6:24

Your question is a bit hard to understand. Are you asking if a PERC 6/E virtual disk running RAID6 can have more then 5 drives? If so, then yes, it can have up to 32 drives in a virtual disk, and you can also group virtual disks. A PERC 6/E can physically support 144 drives.

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