Do you want to remove data device out of existing pool? Before do that , you may list the thin pool to see the track distribution through SE command  symcfg show -pool -thin -sid xx -all   I think starting with lower tracks dev will be better choice. As soon as the devices are disabled, (symconfigure -sid xxx -cmd "disable dev xxx in pool , type=thin;").  It starts draining and the devs are removed from the list of enabled devices. The disabled device enters the Draining state until all the data has been moved. You can still monitor the process using above symcfg show -pool command. Once Draining is completed, the device is in the disabled state. Then you can remove the data device from thin pool.
Hello,  We have around 45 TB of storage in a pool.All the tdat devices are enable.But there is a 12TB of free space.So they are planning to take out of 4TB of space to use for new application.So how many devices we can drain in a single pool?Is there any best practice for draining? I never did a draining process before.What need to be check before doing the draining process.  Your help would be appreciated.  Thanks, Srini
planning to drain a pool