Date: Fri, 19 Feb 2010 15:41:41 -0800 From: Garrett Cooper <yanefbsd@gmail.com> To: Pawel Jakub Dawidek <pjd@freebsd.org> Cc: freebsd-fs@freebsd.org Subject: Re: HAST (Highly Available Storage) now in HEAD. Message-ID: <7d6fde3d1002191541k51ab8526ub18a7c05484112f5@mail.gmail.com> In-Reply-To: <20100219233744.GG1617@garage.freebsd.pl> References: <20100219200725.GA1617@garage.freebsd.pl> <7d6fde3d1002191511h4caac149tf39dcc37cf750afe@mail.gmail.com> <20100219233744.GG1617@garage.freebsd.pl>
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On Fri, Feb 19, 2010 at 3:37 PM, Pawel Jakub Dawidek <pjd@freebsd.org> wrot= e: > On Fri, Feb 19, 2010 at 03:11:44PM -0800, Garrett Cooper wrote: >> =A0 =A0 Very cool stuff. How many nodes max are you targeting for this >> service [...] > > Currently HAST is intended for use only with High Availability clusters, > not for performance clusters and is limited to exactly two nodes - one > primary node, which has access to shared storage and one secondary node, > which just receives updates from primary. User's applications should > only work on primary node. I was looking forward a bit more than what's setup today TBH, but that's ok= ... >> [...] and what are some of the performance numbers for syncing >> across the network (say with a 1GigE or 10GigE connection)? > > HAST should be able to saturate 1GigE link if you have fast enough > storage. I've patches in the works to save data copying between userland > and kernel. Currently, eg. write I/O request comes from the kernel, it > is copied to hastd userland daemon, hastd copies it back to the kernel > when writing to local component and then copies it again to the kernel > when sending over network to secondary node. In other words a lot of > copying. I prototyped a model where data is not copied at all between > userland and kernel, but it needs a bit more work. Ouch. Lots of CoW / copyout...? Is the data being checksummed / verified somewhere to ensure integrity at all (I would think so / hope so...)? Cheers! -Garrett
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