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? Thanks. --Tiernan On Fri, Jul 15, 2011 at 5:39 PM, Edward Ned Harvey < opensolarisisdeadlongliveopensola...@nedharvey.com> wrote: > > From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > > 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 www.tiernanotoolephotography.com www.the-hairy-one.com
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