Date: Tue, 29 May 2012 14:39:13 -0700 From: Freddie Cash <fjwcash@gmail.com> To: Kees Jan Koster <kjkoster@gmail.com> Cc: freebsd-stable@freebsd.org Subject: Re: FreeBSD 9.0 hangs on heavy I/O Message-ID: <CAOjFWZ6X5iMhZuCX4XtM7oRiT0QX%2Bn770KNt46jsU7RmeodGCw@mail.gmail.com> In-Reply-To: <66F196D1-A6D0-437B-886B-2E1A445A69F2@gmail.com> References: <BD5D6BB6-8CFF-456A-B03E-05454EB03AB6@gmail.com> <CAOjFWZ40LX%2B8Lw15mHDG8F3nN0aex5EpqVdjPxRPS89t1Fqkiw@mail.gmail.com> <CAOjFWZ7964oeTNZqADj4cRt3kkdOf5Mwyx8GQDnJnZ8vyONckg@mail.gmail.com> <17320979-2ED2-4DF2-97E9-09035F4DD3BB@gmail.com> <CAOjFWZ7MKE9GJQbUW2OxDSdrNV7Z%2Bp8MApSSb_YWtzWAmYq6_A@mail.gmail.com> <66F196D1-A6D0-437B-886B-2E1A445A69F2@gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, May 29, 2012 at 2:30 PM, Kees Jan Koster <kjkoster@gmail.com> wrote: > Dear Freddie, > >> Granted, I haven't played with gsched yet (most of our high-I/O >> systems are ZFS), so there may be a way to use it across-GEOMs. > > From my previous experiments ZFS suffers the same fate when there is heavy write activity. Reads just don't get served in time. > > How do you deal with that? We're currently only using FreeBSD (and ZFS) on our backups servers. The two main servers do rsync backups for ~150 remote Linux servers and FreeBSD firewalls (1 server does the elementary and secondary schools; the other server does the admin sites). Then they do zfs sends to a third system off-site. Thus, our workloads tend to be fairly one-sided (all reads on the zfs send side; all writes on the zfs recv side; mostly reads on the rsync side side with some writes). And, most of our working set fits into ARC/L2ARC. Cache devices really help, as most reads come from the L2ARC, while most writes go straight through to the pool. We're still a year or so away from our ultimate goal of using FreeBSD+ZFS+NFS to create a separate/proper SAN/NAS tier for our virtual servers. At that point, we'll look a little deeper into things, and experiment with different L2ARC/ZIL setups to optimise read and write paths. -- Freddie Cash fjwcash@gmail.com
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAOjFWZ6X5iMhZuCX4XtM7oRiT0QX%2Bn770KNt46jsU7RmeodGCw>