As I understand matters, from my notes to design the "perfect" home NAS
server :-)
1) you want to give ZFS entire spindles if at all possible; that will
mean it can enable and utilise the drive's hardware write cache
properly, leading to a performance boost. You want to do this if you
can. Alas it knocks out the "split all disks into 7 & 493Gb
partitions" design concept.
2) I've considered pivot-root solutions based around a USB stick or
drive; cute, but I want a single tower box and no "dongles"
3) This leads me to the following design points:
- enormous tower case with 10+ bays
- HE/high-efficency mobo with 8+ SATA capability
- crank down the CPU, big fans, etc... quiet....
- 1x [small/cheap]Gb Drive @ 10000+rpm for root / swap / alternate
boot environments
- 4x 750Gb SATA @ 7200rpm for full-spindle RAID-Z
- populate the spare SATA ports when 1Tb disks hit the price point;
make a separate RAIDZ and drop *that* into the existing pool.
This - curiously - echoes the Unixes of my youth (and earlier!) where
"root" was a small fast disk for swapping and access to key utilities
which were used frequently (hence "/bin" and "/lib") - whereas "usr"
was a bigger, slower, cheaper disk, where the less frequently-used
stuff was stored ("/usr/bin", home directories, etc)...
Funny how the karmic wheel turns; I was suffering from the above
architecture until the early 1990s - arguably we still suffer from it
today, watch Perl building some time - and now I am redesigning the
same thing but at least now the whole OS squeezes into the small disk
pretty easily. :-)
As an aside there is nothing wrong with using ZFS - eg: a "zvol" - as a
swap device; but just as you say, if we use real disks for root then
they will be so big that there's probably no point in pushing swap off
to ZFS.
-a
--
Alec Muffett
http://www.google.com/search?q=alec-muffett
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