Some experience about ZFS

ZFS is a good file system, it can manage lots of disks.
I have three 1G harddisks when I use ZFS beginning. In accordance with my experience, raid 5 is my first choice. Raid 5 is called raidz in ZFS. Suppose my pool is named nas, I created this pool by the following command:

zpool create nas raidz c9d0t0 c9d1t0 c9t2d0

After create pool, check the pool statu:

$ zpool status -v nas
  pool: nas
 state: ONLINE
 scrub: none requested
config:
 
        NAME        STATE     READ WRITE CKSUM
        nas         ONLINE       0     0     0
          raidz1-0  ONLINE       0     0     0
            c9t0d0  ONLINE       0     0     0
            c9t1d0  ONLINE       0     0     0
            c9t2d0  ONLINE       0     0     0
 
errors: No known data errors

It’s time to consider to expand the capacity when this pool is full.

After I get a 2G harddisk, I have two choice:
1.replace a old disk in the pool;
2.Add the new disk into the pool.

I wouldn’t waste a disk, so I choose the second.

I checked some document, raidz don’t support add a new disk to raidz. If I use the following command:

zpool add nas c9t3d0

the new disk will add to the pool by raid 0. It isn’t what I want.

So, the raid 1 + 0 is recommended in the future.
Create raid1 pool first. Create another raid1 and add the new mirror to the old pool by raid0, when it need to add new disks.

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