[attempt to clean up the text, sorry if I miss something]
James Dickens wrote:
On 1/12/07, Kyle McDonald <[EMAIL PROTECTED]> wrote:
Patrick P Korsnick wrote:
i just set up snv_54 on an old p4 celeron system and even tho the
processor is crap, it's got 3 7200RPM HDs: 1 80GB and 2 40GBs. so i'm
wondering if there is an optimal way to lay out the ZFS pool(s) to
make this old girl as fast as possible....
>
> as it stands now i've got the following drive layout:
>
> pri master: 80GB (call it drive1)
> pri slave: 40GB (drive 2)
>
> sec master:40GB (drv 3)
> sec slave: DVD
>
> (all connected with 80 conductor ribbons)
>
> my partitions are:
> drive 1: i've got 2 10GB UFS root slices (so i can do live
> upgrades), and 1GB swap slice
> i've got one big zpool consisting of a 50GB slice on drive 1 and all
> of drives 2 & 3.
>
> i'm not sure that this is the optimal layout for striping. i don't
> need mirroring or
> redundancy-- just speed. i'm thinking maybe i'd be better booting
> off one of the smaller >>drives and putting the other two on one
> controller and putting the zpool on those only. >> spanning the two
> IDE controllers with the single zpool seems like it might be a bad
> idea, but i am just postulating here....
that is backwards, you want them split, on each controller, in case
one controller chip dies the data still remains in tact and safe if
they the two drives are mirrored.
It is not a good assumption that if you have two IDE controllers that you
have two IDE controller chips. In fact, I can't remember the last time
I saw such a beast... 1997 perhaps? Don't worry about the controllers.
See http://blogs.sun.com/relling/entry/zfs_raid_recommendations_space_vs
for most the space, availible with safety, take a 40GB slice off the
80GB drive, and combine with the other 2x 40GB drives in a raidz group
composed of 3x 40GB pieces that gives you about 80GB of usable disk
space.
>
your other choice is 2x 40GB drives together mirrored in one pool, so
it can survive the loss of a drive and still maintain data. and use
the remaining slice off the 80GB drive as a single drive pool that
holds temporary data that isn't important because the data is gone if
the drive dies.
And a third choice is cutting your 40GByte drives in two such that you
have a total of 6x 20 GByte partitions spread across your 80 and 40 GByte
drives. Then install three 2-way mirrors across the disks. Some people
like such things, and there is merit to such designs.
disk1 20 GBytes <- mirror -> disk2 20 Gbytes
disk2 20 GBytes <- mirror -> disk3 20 Gbytes
disk3 20 GBytes <- mirror -> disk1 20 Gbytes
total available space: 60 GBytes. Better performance for some workloads
than raidz.
BTW, I recently bought a 160 GByte IDE disk, new in the box for $20 from a
major retail chain. If it were my choice, I'd spend $20.
-- richard
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