The potential road-block that I’d look out for is whether the on-board SATA that is currently in the box is supported by SmartOS/illumos. If not, then it would be a matter of dropping a compatible HBA (LSI SAS are the crowd favourite) with a SAS->SATA fan-out.
Running a Windows KVM with a database server on SATA disks without an SLOG is a bit of a recipe for bad performance. That being said, it obviously depends on the underlying zpool layout/disk characteristics/database performance expectations and workload. It is worth noting that all writes inside a KVM are treated as synchronous writes, which is what drags performance down. This can be mitigated by using an SSD-based SLOG. The degree to which it is mitigated depends on the performance of the SSD you use - the lower latency/higher IOPS the drive offers, the better the result. I would also look for an SSD with power protection/super caps, just to be sure your writes are actually available form the SLOG should the worst happen. I’m not aware of any SmartOS users using PCI-SSDs and I’m not sure they are supported (beyond SATA/SAS drive emulation). There is some activity within illumos around building an NVMe driver to take full advantage of PCI based SSDs. AFAIK, most people use either a SATA/SAS based SSD. A popular SATA drive is the Intel DC S3700 200GB model (has higher IOPS/throughput than the 100GB) and we’ve just been deploying HGST Ultrastar SSD800MH.B drives and are seeing write speeds of 477 MB/sec inside a KVM. You’ll certainly see better overall performance by using mirrors rather than RAIDZ and for 4 disks it would probably be your best option overall. It would probably be worth just trying what you have now and seeing if it works to a satisfactory level. Keep in mind that ZFS has ARC and will use RAM to cache your most common writes. Ideally, much of the data involved in the database should be fed from RAM rather than real reads from disk, so your read requirements might not be that high in reality. > On 16 Jun 2015, at 12:49 PM, Jack Downes <[email protected]> wrote: > > I'd have to echo Sebastian mostly. Zfs is great, but the underlying hardware > is... what is. add another 1 tb drive and put that as Raid 10 (stripe the > mirrors), and it'll perform pretty decently. You'd be surprised. If you have > the money, yeah, SSD is fantastic, but wow... if you are trying to get > reasonable size, you'll spend some cash. Perhaps in this case that doesn't > matter. If you have the money for SSD drives, you might consider getting 4 > reasonable 2TB drives (they sell them for $50 each on gohardrive.com anymore > for WD RE4 or Hitachi Ultrastars now), and then putting some budget into a > smartOS compatible PCI-SSD drive. Be careful on that - it's easy to get the > wrong drive, but it's not that hard to get the right one either! That way > you'd have your 4 spindles, raid 10 with a slog, it'd be decent that way, > IMHO. > > On 06/15/2015 07:07 PM, [email protected] wrote: >> one of my clients owns a supermicro-based box with 4 hot-swap sata bays. it >> has integrated SATA and (i believe) no SAS. the original admin populated it >> with (3) 1TB SATA disks and commissioned it as a fileserver (simple raid5). >> it has 32GB of memory. the box is no longer being used, so it's been >> allocated to me for the purpose of hosting another windows server. i'd like >> to virtualize the server via smartos/kvm but i have reservations. >> >> i believe i can get away with using only 16GB for VMs, so that leaves 16GB >> for smartos/zfs - i think that'll probably work well. but i seriously doubt >> those disks will give anything resembling decent performance. i only have 4 >> bays to work with, and only one is currently free. for a windows server VM >> hosting a multi-user database, would adding a SATA SSD as log device for the >> zones zpool keep me out of hot water here or is this just not going to work? >> >> obviously i can try to source a supported SAS controller and disks, but i'm >> wondering if i can actually get by with SATA ... what if i filled the (4) >> 3.5" bays with SSDs and striped across two mirrors? would that mostly >> guarantee decent performance, or will that just waste time and money? >> >> experienced opinions greatfully accepted! >> >> >> ------------------------------------------- >> smartos-discuss >> Archives: https://www.listbox.com/member/archive/184463/=now >> RSS Feed: https://www.listbox.com/member/archive/rss/184463/26849696-e427f2da >> Modify Your Subscription: https://www.listbox.com/member/?&; >> Powered by Listbox: http://www.listbox.com > > -- > Jack Downes > > > > ------------------------------------------- > smartos-discuss > Archives: https://www.listbox.com/member/archive/184463/=now > RSS Feed: https://www.listbox.com/member/archive/rss/184463/25738179-216c4b5f > Modify Your Subscription: https://www.listbox.com/member/?&; > Powered by Listbox: http://www.listbox.com ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
