That&#x27;s not a hidden cost. That&#x27;s what you&#x27;d normally expect with any traditional RAID. However like many modern solutions, ZFS does have a few workarounds:<p><pre><code>   MULTIPLE ARRAYS PER TANK
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If you have space in your storage servers housing, then you can buy multiple disks at a time as a separate array (eg 3 disk raidz1) and add them to your existing &quot;tank&quot; (ie storage pool).<p><pre><code>   AUTOEXPANDING INTO LARGER DISKS
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If you have <i>autoexpand=on</i> set on your tank then you can upgrade the capacity of each disk in a raidz, one disk at a time. The caveat here is that your array doesn&#x27;t increase in capacity until every disk has been upgraded, but it does still allow you to start the upgrade process incrementally.<p><pre><code>   ALTERNATIVE SOLUTIONS
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However, if one needs the support of upgrading their array, increasing the capacity with each new disk added, then ZFS is definitely the wrong choice. Any traditional RAID array would be ill suited for this. Instead I would recommend unRAID or similar (I think Windows might have something built in, but I&#x27;m a UNIX guy so couldn&#x27;t comment there).