I was recently evaluating much the same question but with out only a single pool and sizing my disks equally.
I only need about 500GB of usable space and so I was considering the value of 4x 250GB SATA Drives versus 5x 160GB SATA drives. I had intended to use an AMS 5 disk in 3 5.25" bay hot-swap backplane. http://www.american-media.com/product/backplane/sata300/sata300.html I priced Seagate 250GB and 160GB SATA drives at $70 and $54 USD each, respectively. The backplane runs about $130. The config options I considered are: RZ1 +spare RZ2 -spare mirror(s) (+spare w/ 5 160GB disks) Using Richard's blogs to help my evaluation I made the following conclusions between the choices... - Mirrors cost you 50% of your total space, but give you the best performance and "average" fault tolerance. - RZ1+spare gives you the same space (2 data, 1 parity, 1 spare w/ 4 disks), middle of the road performance and the worst fault tolerance. - RZ2 gives you the same space as well (2 data, 2 parity w/ 4 disks), the worst performance and the best fault tolerance. - spares give you negligible benefit over time with respect to cost. What I mean by this is that for the "home" environment, if a disk costs $100 today, next year it will cost $80, the year after even less. Paying up front for a relatively small increase in reliability that declines quickly as time goes on is probably not a good "value" decision. In addition, they are readily available in most populated areas if you can't wait for warranty replacement...and Seagate offers 5 yr warranty (which is why I spec'd Seagate not WD). My conclusion was to go with 4x 250GB in a single pool with two mirror vdevs. Overall I'd suggest that you scale your disks to be in proportion with your target total usable size and keep it simple and to an even number of disks. I still have yet to purchase the system due to my issues with finding the right board with the right SATA controller. My desktop system at home runs an nVidia 590a chipset on a Foxconn motherboard and Solaris U3 will only recognize the DVD drive during installation. A side note to that compatibility issue... quick/dirty solution to the SATA controller issue... install VMWare Server and configure VMWare to supply the guest raw disks. VMWare Server provides a nice hardware abstraction layer that has turned my a partition on my SATA disk into a SCSI hard drive that Solaris interacts with swimmingly. I loose a little system resource to Host OS and VMWare overhead, but at least I have a fully time Solaris system running on my home network on hardware it would not otherwise agree with. On 9/27/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > Date: Thu, 27 Sep 2007 10:10:24 PDT > From: Christopher <[EMAIL PROTECTED]> > Subject: Re: [zfs-discuss] Best option for my home file server? > To: zfs-discuss@opensolaris.org > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=UTF-8 > > Hmm.. Thanks for the input. I want to have the most space but still need a > raid in some way to have redundancy. > > I've added it up and found this: > ggendel - your suggestiong makes me "loose" 1TB - Loose 250GBx2 for the > raid-1 ones and then 500GB from a 3x500GB = 1TB > bonwick - your first suggestion makes me "loose" 1TB. The second 750GB. The > third, still 750GB but I gain 500GB more, since I know only loose 1/3 of 1500 > instead of 1/2 of 1000. > > ggendel - yeah I know you would degrade both pools, but you would still be > able to recover, unless our good friend Murphy comes around in between, as I > would expect him to :-/ > > So, as bonwick said - let's keep it simple :) No need to make it very complex. > > How is SATA support in OpenSolaris these days. I've read about ppl saying it > has poor support, but I believe it was blogs and suchs from 2006. I > downloaded the Developer Edition yesterday. > > I can have 10 SATA disks in my tower (8 onbord sata connections and 2 from a > controller card). Why not fill it :) > > I made a calculation, buying 1x500+3x750, 4x750 or 4x500 disks. The price/GB > doesn't differ much here in Norway. > > Option 1 - Buying 4x750GB disks: > 4x250 RaidZ - 750/250 (Raid size/lost to redundancy) > 2x500 Raid1 - 500/500 > 4x750 RaidZ - 2250/750 > Equals: 3500/1500 (3500GB space / 1500GB lost to redundancy) > Cost: 4x750 costs NOK6000 = US$1100 > > Option 2 - Buy 1x500 + 3x750 > 4x250 RaidZ - 750/250 > 3x500 Raid1 - 1000/500 > 3x750 RaidZ - 1500/750 > Equals 3250/1500 > 1x750 costs NOK 1500 = US$ 270 > 3x500 costs NOK 3000 = US$ 550 > Total US$ 820 > > Option 3 - Buying 4x500GB disks: > 4x250 RaidZ - 750/250 > 6x500 Raid1 - 2500/500 > Equals: 3250/750 > Cost: 4x500 costs NOK4000 = US$ 720 > > Option 2 is not winning in either cost or space, so thats out. > Option 1 gives me 250GB more space but costs me NOK 2000 / US$ 360 more than > option 3. For NOK 2000 I could get two more 500GB disks or one big 1TB disk. > > Obviously from a cost AND size perspective it would be best/smart to go for > option 3 and have a raidz of 4x250 and one of 6x500. > > Comments? > > > This message posted from opensolaris.org > > _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
