The ZIL is a write-only log that is only read after a power failure. Several GB
is large enough for most workloads.
You can't use the Intel X25-E because it has a 32 or 64 MB volatile cache that
can't be disabled neither flushed by ZFS.
Imagine your server has a power failure while writing da
J4200 is cheap compared to custom made solutions (Supermicro + 3Ware). Ask a
Sun reseller for a quote. There is also the Sun Startup Essentials program with
great prices on storage systems.
Last year I've bought an Infortrend RAID array with custom disks but today I
would choose a J4400 + 24 T