On Mar 17, 2010, at 10:41 AM, Brad Nicholson wrote: > On Wed, 2010-03-17 at 09:52 -0400, Justin Pitts wrote: >> FusionIO is publicly claiming 24 years @ 5TB/day on the 80GB SLC device, >> which wear levels across 100GB of actual installed capacity. >> http://community.fusionio.com/forums/p/34/258.aspx#258 >> > > 20% of overall capacity free for levelling doesn't strike me as a lot.
I don't have any idea how to judge what amount would be right. > Some of the Enterprise grade stuff we are looking into (like TMS RamSan) > leaves 40% (with much larger overall capacity). > > Also, running that drive at 80GB is the "Maximum Capacity" mode, which > decreases the write performance. Very fair. In my favor, my proposed use case is probably at half capacity or less. I am getting the impression that partitioning/formatting the drive for the intended usage, and not the max capacity, is the way to go. Capacity isn't an issue with this workload. I cannot fit enough drives into these servers to get a tenth of the IOPS that even Tom's documents the ioDrive is capable of at reduced performance levels. >> Max drive performance would be about 41TB/day, which coincidently works out >> very close to the 3 year warranty they have on the devices. >> > > To counter that: > > http://www.tomshardware.com/reviews/fusioinio-iodrive-flash,2140-2.html > > "Fusion-io’s wear leveling algorithm is based on a cycle of 5 TB > write/erase volume per day, resulting in 24 years run time for the 80 GB > model, 48 years for the 160 GB version and 16 years for the MLC-based > 320 GB type. However, since 5 TB could be written or erased rather > quickly given the performance level, we recommend not relying on these > approximations too much." > I'm not sure if that is a counter or a supporting claim :) > >> FusionIO's claim _seems_ credible. I'd love to see some evidence to the >> contrary. > > Vendor claims always seem credible. The key is to separate the > marketing hype from the actual details. I'm hoping to get my hands on a sample in the next few weeks. > > Again, I'm just passing along what I heard - which was from a > vendor-neutral, major storage consulting firm that decided to stop > recommending these drives to clients. Make of that what you will. > > As an aside, some folks in our Systems Engineering department here did > do some testing of FusionIO, and they found that the helper daemons were > inefficient and placed a fair amount of load on the server. That might > be something to watch of for for those that are testing them. > That is a wonderful little nugget of knowledge that I shall put on my test plan. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
