2011-07-16 15:46, Tiernan OToole ?????:
Thanks for the info. need to rebuild my machine and ZFS pool.... kind
of new to this and realized i built it as a stripe, not a mirror...
also, want to add extra disks...
As a follow up question:
I have 2 500Gb internal drives and 2 300Gb USB drives. If i where to
create a 2 pools, a 300Gb and a 500Gb in each, and then mirror over
them, would that work? is it even posible? or what would you recomend
for that setup?
Is there a typo? It would rather be a 2*300Gb mirror and a 2*500Gb mirror,
with a "stripe" above them as much as writes can get balanced.
That would work (with forcing on command-line), is possible, moderately
recommmended because unbalanced setups can have more issues than
usual (hence you must use the force to enable such setup).
And just in case, this pool can not be a bootable rpool.
You might make a 2*200Gb slice mirror for an rpool and a more balanced
4*300Gb pool of any layout (raid10, raidz123)...
As for using USB sticks, I started my unlucky setup with some sticks used
as L2ARC, and about once a week the device got lost (possibly because
a stick could slide a bit from its contact bay on the chassis - BIOS
also did
not see the stick until it was re-plugged). Loss of a device would also hang
my pool for quite a long while...
Thanks.
--Tiernan
On Fri, Jul 15, 2011 at 5:39 PM, Edward Ned Harvey
<opensolarisisdeadlongliveopensola...@nedharvey.com
<mailto:opensolarisisdeadlongliveopensola...@nedharvey.com>> wrote:
> From: zfs-discuss-boun...@opensolaris.org
<mailto:zfs-discuss-boun...@opensolaris.org> [mailto:zfs-discuss-
<mailto:zfs-discuss->
> boun...@opensolaris.org <mailto:boun...@opensolaris.org>] On
Behalf Of Tiernan OToole
>
> This might be a stupid question, but here goes... Would adding,
say, 4 4
or
> 8gb usb keys as a zil make enough of a difference for writes on
an iscsi
shared
> vol?
>
> I am finding reads are not too bad (40is mb/s over gige on 2
500gb drives
> stripped) but writes top out at about 10 and drop a lot lower...
If I
where to
> add a couple usb keys for zil, would it make a difference?
Unfortunately, usb keys, even the fastest ones, are slower than
physical
hard drives. I even went out of my way to buy a super expensive
super fast
USB3 16G fob... And it's still slower than a super-cheap USB2
sata hard
drive.
There is a way you can evaluate the effect of adding a fast slog
device
without buying one. (It would have to be a fast device, certainly
no USB
fobs.) Just temporarily disable your ZIL. That's the fastest you can
possibly go. If it makes a big difference, then getting a fast
slog device
will help you approach that theoretical limit. If it doesn't make
a huge
difference, then adding slog will not do you any good.
To disable ZIL, if your pool is sufficiently recent, use the zfs
set sync=
command. It takes effect immediately. If you have an older
system, you'll
have to use a different command, and you'll probably have to
remount your
filesystem in order for the change to take effect.
--
Tiernan O'Toole
blog.lotas-smartman.net <http://blog.lotas-smartman.net>
www.tiernanotoolephotography.com <http://www.tiernanotoolephotography.com>
www.the-hairy-one.com <http://www.the-hairy-one.com>
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