ZFS Best Practices Questions

[azev]

So, I recently build a new zfs servers with 12x 12 sata drives in 2 x RAIDZ2 vdevs. The purpose of the server is for a dedicated cifs/smb filers and NFS mounts for both windows/linux machines. Currently the servers have a RMS-200 NVRAM Drive as zil and SYNC=ENABLED, but I am curious whether this is necessary or not ?
I recently come across gea post where he said there's no benefit in enabling sync=enabled for a dedicated zfs filer and I just want to confirm that this is the case before I started making changes to the pool as I am planning to upgrade them during the holiday season.

I also have a questions regarding expanding the pool as they are about 70% populated right now; I am thinking of getting another 12 Drives (24bay case with SAS expander) and wonder what would be the best strategy to add additional capacity to this server;
Should I expand the current pool and add 2 more vdev of raidz2 ? or should I create a completely new pool with similar layout ?
Anyone care to list pros/cons of the above options ?
The performance of the pool as it is configured right now its acceptable, so I am really only looking to add capacity instead of searching for more performance.
What if I found a good deal for a higher capacity drives ?? should this changed the decision on the pool layout ?

Thanks

 

[gea]

There are two options to extend capacity of a ZFS pool_

1.) add another vdev
you can add any vdev type but usually you add another of same type

2. replace all disks with larger ones

While expander + Sata disks works, on a "production system" you should use SAS disks due a better behaviour on "single bad disks that may block the whole system" or a longer allowed cable length with a more stable connectivity.

 

[azev]

Interesting I never knew sata based array with expander can have issues with "single bad disks that may block the whole system". Luckily so far I have not experienced this, knock on wood hopefully its not going to happen anytime soon. Anyway thanks for the advice.