On 11/9/2011 8:05 AM, Edward Ned Harvey wrote:
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of Ding Honghui

But now, as show below, the first 2 raidz1 vdev usage is about 78% and the
last 2 raidz1 vdev usage is about 93%.
In this case, when you write, it should be writing to the first two vdevs,
not the last two.  So the fact that the last two are over 93% full should be
irrelevant in terms of write performance.

All my file is small files which size is about 150KB.
That's too bad.  Raidz performs well with large sequential data, and
performs poor with small random files.

Now the questions is:
1. Should I balance the data between the vdevs by copy the data and remove
the data which locate in last 2 vdevs?
If you want to.  But most people wouldn't bother.  Especially since you're
talking about 75% versus 90%.  It's difficult to balance it so *precisely*
as to get them both around 85%

2. Is there any method to automatically re-balance the data?
There is no automatic way to do it.
For me, this is a key issue. If there was an automatic rebalancing mechanism, that same mechanism would work perfectly to allow pools to have disk sets removed. It would provide the needed basic mechanism of just moving stuff around to eliminate the use of a particular part of the pool that you wanted to remove.

Gregg Wonderly
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