based on our performance requirement , I think I only want to expand the capacity not performance, that's the reason I believe NL-SAS Raid 6 is fit for my requirement (as you know , the cost control is the main reason as well).

so what i want is migration the currently Raid5 SAS 15K filesystem data to Raid6 NL-SAS, for release the performance disks for other critical service.

but I have no idea is that possible

Thank you

is there a reason for not considering FAST(fast vp) storage tiering?. This indeed not faster than FS migration, but for long term it can address more similar situations you may have in future.

Clariion LUN migrator is the tool/feature you can use for migrating data online from storage side, w/o any down time on host side or rather completely transparent. It comes with flare and should be available in VNX as well.

after the migration old LUN will be automatically destriyed and new LUN( not in any storage group, it can be in another RG, another disk type , even another raid type) will take the complete identify of the old one.

slect the LUN to migrate and chose "migrate" and you chose migration rate to a lower one  than high since you r doing it first time and not to worry about the "impact" during the migration

1. No, you cannot mix r5 with r6 under such kind of situation.

2. LUN Migration is one of the option. But there are so many restrictions. You must migrate the SAS 15K r5 LUN to another SAS r5 LUN, otherwise, VNX-File cannot recognize the new LUN. So the only option for you is to copy the data from the source to the target lun over file-level protocol (cifs/nfs/ftp)

VNX LUN Migrations are supported, but only under the following criteria. These are restrictions which MUST be followed carefully, otherwise data outages or data loss can be incurred. 

When LUNs in a Celerra storage group are greater than an HID of 15, the following rules apply to LUN migrations with regards to data LUNs:

The RAID type is the same (for example, RAID 5 RAID5, or RAID 3  RAID 3)

(NOT RAID 5 -> RAID 3 or RAID 3 -> RAID5)
 
The drive type is similar.

(FC allowed to FC), (ATA allowed to ATA)
 
The number of the physical drives in the RAID group is the same.

(Source and target RAID groups)
 
The source and target LUNs must be identical size

(According to block count size, not MB size)

Refer to emc144545, there are some rules apply to LUN migrations on a Celerra server.

• The RAID type is the same (for example, RAID 5 RAID5, or RAID 3  RAID 3)
• The drive type is similar.
• The number of the physical drives in the RAID group is the same.
• The source and target LUNs must be identical size

I'm not sure if they apply to VNX File as well. But you'd better be cautious when taking actions. If you just want to release some performance disks, why not create a new filesytem instead of expand the old one? Some host-based file transfer tools, such as EMCopy, Robocopy, might be safer.

Yes the rules for LUN migration still apply

Look for a supported and working method

Like creating a new fs of the desires RAID type or tiered data and copy or replicate the data