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San migration

Created: 03 May 2013 • Updated: 06 May 2013 | 9 comments
This issue has been solved. See solution.

Hi Guys, I have one concat volume say vol01. I am planning to create a striped plex on new storage devices and attach it to the existing volume vol01 and mirror it with existing concate plex. Kindly let me know if it feasible to perform.

Your help is apreciated.

Thanks

Operating Systems:

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mikebounds's picture

Yes this is fine - volume manger allows different layouts on plexes.  The syntax would be something like:

vxassist -g diskgroup mirror vol_name layout=striped

Mike

UK Symantec Consultant in VCS, GCO, SF, VVR, VxAT on Solaris, AIX, HP-ux, Linux & Windows

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nitj's picture

Thanks Mike, Also could you please let me what would be syntax for creating mirror or striped plex of 16 column with 64 each 33gb disks.

mikebounds's picture
vxassist -g diskgroup mirror vol_name layout=striped ncol=16 stwidth=64 !newdisk_name

Mike

UK Symantec Consultant in VCS, GCO, SF, VVR, VxAT on Solaris, AIX, HP-ux, Linux & Windows

If this post has answered your question then please click on "Mark as solution" link below

nitj's picture

Sorry mike, i meant with ncol=16 with 64 disks. Do I have to specify all 64 disks while creating mirror or striped plex ?

nitj's picture

And currently I am planning like below :

Create subdisks on each 64 disks, by taking whole disk.

vxmake -g DG sd disk01-01 disk01,0,33g

Create plex as follows:

vxmake -g DG plex "Plex name" layout=striped ncol=16 sd=disk1,disk2...disk64

vxplex -g DG att Plex Volume

mikebounds's picture

Why use lower level commands?  If you use vxassist, then you probably don't need to specify disks as vxassist will try to mirror across controllers and your new array will show up on a different controller.  If you want to verify that vxassist will do the right thing, then just create a small concat volume (like 100m) on your existing array and then run:

vxassist -g diskgroup mirror vol_name layout=striped ncol=16

This should create a mirrored plex across 16 of your disks on the new array.

As you are using 64 disks, I am assuming your existing volume is just over 2TB (33*64GB) so if you mirror this volume using vxassist it will use 64 disks.

If you don't want vxassist to create a layered volume, then you can edit/create /etc/default/vxassist with:

stripe-mirror-col-trigger-pt=262144g
stripe-mirror-col-split-trigger-pt=262144g

This stops all volumes been layered.

Mike

UK Symantec Consultant in VCS, GCO, SF, VVR, VxAT on Solaris, AIX, HP-ux, Linux & Windows

If this post has answered your question then please click on "Mark as solution" link below

nitj's picture

Yes Mike file system is around 2TB. We wanted to play safe by creating subdisks, plex , since we are sure we will have one concat plex and one striped plex by this way.

Could you please explain me below things:

"If you don't want vxassist to create a layered volume, then you can edit/create /etc/default/vxassist with:

stripe-mirror-col-trigger-pt=262144g
stripe-mirror-col-split-trigger-pt=262144g

This stops all volumes been layered."

Thanks

mikebounds's picture

Layered volume give exact same performance and the data is in exactly the same place as non-layered, but VM creates more objects which means it is more complicated, but gives more reliance as more disks can fail without the volume failing.   But if this is just a migration step, then I guess you will delete the plex on the old array, so there is no point in a layered volume and actually, the volume could not be created as layered as this requires both plexes to be stripes.  Layered volumes are created where possible over a certain size, but you can override this trigger point as in my last post to the largest possible volume so layered volumes are disabled.

Mike

UK Symantec Consultant in VCS, GCO, SF, VVR, VxAT on Solaris, AIX, HP-ux, Linux & Windows

If this post has answered your question then please click on "Mark as solution" link below

SOLUTION
nitj's picture

Thanks Mike, for your valueable inputs,

 I will be using either

vxassist -g diskgroup mirror vol_name layout=striped ncol=16

or if it creates any problem then might go with low lable commands.

Thanks.