I've been told by quite a few folks that splitting the SSD between log and cache is "a bad idea" or "suboptimal" but frankly, I don't buy it. It may just be my personal experience, but for my use cases, I've been operating with limited resources and haven't been able to justify the expense of having three or more SSDs to do this. Since I've never needed a ZIL with more than 2 GB of space and the smallest SSDs you can buy are more than 10x that size, mirroring a pair of SSDs for the ZIL was a huge waste of space. I started doing this about 4 years ago when SSDs were much more expensive and I couldn't justify that waste, so I'd partition a 1-2 GB slice on each SSD and mirror them for my ZIL, and use the remaining space on both SSDs, un-mirrored, for cache. Again, in my experience, this has always resulted in better general performance than either adding only log or only cache.
YMMV. On Fri, Jan 19, 2018 at 1:07 AM, Ian Collins <[email protected]> wrote: > On 01/19/2018 08:45 PM, Jim Wiggs wrote: > >> So all is right with the world again. But I'm still left with one >> question: why on Earth is *parted* not included as part of the SmartOS >> hypervisor image? The old Solaris format command is spectacularly >> user-unfriendly and always has been. I can't imagine that parted requires >> so much additional space that it couldn't be included. Was there any >> particular rationale to not put a better and more user-friendly >> partitioning tool into the OS that runs at the top level and manages the >> hardware? >> >> > As Jussi said, partitioning disks on a ZFS only system is uncommon. > > Splitting an SSD between log and cache generally isn't a very performant > option. Devices that make good cache devices may not be good logs. With > SmartOS running KVM, there is a big gain from log devices, but not much > from a cache. > > Cheers, > Ian. > ------------------------------------------- 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
