Hello all,

  For smaller systems such as laptops or low-end servers,
which can house 1-2 disks, would it make sense to dedicate
a 2-4Gb slice to the ZIL for the data pool, separate from
rpool? Example layout (single-disk or mirrored):

s0 - 16Gb - rpool
s1 - 4Gb  - data-zil
s3 - *Gb  - data pool

  The idea would be to decrease fragmentation (committed
writes to data pool would be more coalesced) and to keep
the ZIL at faster tracks of the HDD drive.

  I'm actually more interested in the former: would the
dedicated ZIL decrease fragmentation of the pool?

  Likewise, for larger pools (such as my 6-disk raidz2)
can fragmentation and/or performance benefit from some
dedicated ZIL slices (i.e. s0 = 1-2Gb ZIL per 2Tb disk,
with 3 mirrored ZIL sets overall)?

  Can several ZIL (mirrors) be concatenated for a single
data pool, or only one dedicated ZIL vdev can be used?

//Jim Klimov

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