MD3000 series doesn't seem to have raid 6 support, which could be very useful with lots of sata drives. Also MD3000i doesn't specify LACP support for the dual or quad Ethernet ports on the enclosure. But a pe1950 + perc 6 with MD1000 has raid 6 support and the OSS can benefit from good ethernet bonding support in Linux. I have a setup with eight MD1000s on two perc 5's on two OSS.
Balagopal Nick Jennings wrote: > Hi Brian! Thanks for the reply, comments below > > Brian J. Murrell wrote: > >>> Instead of just adding another 1TB server, I need to plan for a more >>> scalable solution. Immediately Lustre came to mind, but I'm wondering >>> about the performance. Basically our company does niche web-hosting for >>> "Creative Professionals" so we need fast access to the data in order to >>> have snappy web services for our clients. Typically these are smaller >>> files (2MB pictures, 50MB videos, .swf files, etc.). >>> >> Well, I'm not sure those files would fall within our general >> classification of "small files" (wherein we know we don't perform very >> well). Our small-file issues are usually characterized by "kernel >> builds" and ~ use, where files are usually much smaller than 1MB. >> > > Aha, OK well then that's good to know. There's also some kind of > read-ahead and client side caching right? So files which are accessed a > lot will be faster to access. > > > >>> Also I'm wondering about the best way set this up in terms of speed >>> and ease of growth. I want the web-servers and the storage pool to be >>> independent of each other. So I can add web-servers as the web traffic >>> increases, and add more storage ass our storage needs grow. >>> >> Well, your web-servers would be Lustre clients. There is no >> relationship, or rather requirements in terms of the number of clients >> and servers being used. You use as many servers as your client load >> demands. So you could imagine both ends of the spectrum where only a >> relatively few clients could be used to tax quite a few servers or the >> opposite where a lot of clients with modest demand requires only a few >> servers. >> >> >>> I was thinking initially we could start with 2 servers, both attached >>> to the storage array. setup as OSS' and functioning as (load balanced) >>> web-servers as well. >>> >> Sounds like you are describing 2 storage servers, which would require at >> least 3 servers total. Don't forget about the MDS. Also don't forget >> about HA if that's a concern for you. You could make the 2 OSSes >> failover partners for each other if you are willing to accept a possibly >> lower performance impact when one of the OSSes failing. >> >> If HA is important to you however, you need to address an MDS failover >> with a second server to pick up the MDT should the active MDS fail. >> > > HA is definitely critical, if the storage pool becomes inaccessible we > loose clients (and all fingers point at me!). However, I need to find a > reasonable balance between cost / scalability / performance. The idea > would be to start small, with the simplest configuration, but allow for > a lot of growth. In a years time, if we are using 5TB of data, we will > be in a very good position financially and can afford a systems expansion. > > So for starters, what can I get away with here? 1 OSS, 1MDS & 1 Client > node? Is it a smart thing to do to have the MDS and OSS share the same > storage target (just a separate partition for the MDS)? What kind of > system specs are advisable for each type (MDS, OSS & Client node) as far > as RAM, CPU, disk configuration etc? Also, is it possible to add more > OSS' to take over existing OSTs that another OSS was previously > managing? ie. if I have the MD3000i split into 5x1TB volumes (5xOSTs), > and the OSS is getting hammered, I set another OSS up and hand off 2 or > 3 OSTs from the old OSS to the new one, and set it up as failover for > the remaining OSTs. Do-able? > > > > >> As for OSSes being web-servers, that would require the OSS/Webservers >> also be clients and that is an unsupported configuration due to the risk >> of deadlock due to memory pressure. The recommended architecture would >> be to make the webservers Lustre clients. >> > > I see, so from the get-go I'm going to need an internal gigE network for > OSS/Client communication. > > > >>> performance can I expect, am I out of touch to expect something similar >>> to a directly attached RAID array? >>> >> I think our generally talked about numbers are something on the order of >> achieving 80% of the raw storage bandwidth (assuming a capable network >> and so on). Maybe somebody who is closer to the benchmarking that we >> are constantly doing can comment further on how close-to-raw-disk we are >> achieving lately. >> > > Is it safe to say my bottleneck is going to be the OSS & not the > network? Is there some documentation I can read about typical setups, > usage cases & methods for optimal performance? > > Thanks! > -Nick > _______________________________________________ > Lustre-discuss mailing list > [email protected] > http://lists.lustre.org/mailman/listinfo/lustre-discuss > _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
