Hi Carlos, > In my experience SSDs didn't help much, since the MDS bottleneck is not > only a disk problem rather than the entire lustre metadata mechanism.
Yes, but one does not need much space on the MDS and four SSDs (as MDT) are way cheaper than a RAID controller with 10 15K disks. So the question is basically how the DRDB latency will influence the MDT performance. I know sync/async makes a big difference here, but I have no idea about the performance impact of both or how the reliability is influenced. > One remark about DRDB: I've seen customers using it, but IMHO, if > Active/standby HA type configuration would be more reliable and will > provide you a better resilience. Again, don't know about your uptime and > reliability needs, but the customers I've worked with that requires > minimum downtime on production, always go for RAID controllers rather than > DRDB replication. OK, thanks. That is a good information. So SSD+DRDB are considered to be the "cheap" solution. Even for small clusters? Regards, Michael > > Regards, > Carlos. > > > -- > Carlos Thomaz | Systems Architect > Mobile: +1 (303) 519-0578 > ctho...@ddn.com | Skype ID: carlosthomaz > DataDirect Networks, Inc. > 9960 Federal Dr., Ste 100 Colorado Springs, CO 80921 > ddn.com<http://www.ddn.com/> | Twitter: @ddn_limitless > <http://twitter.com/ddn_limitless> | 1.800.TERABYTE > > > > > > On 1/22/12 12:04 PM, "Michael Kluge"<michael.kl...@tu-dresden.de> wrote: > >> Hi, >> >> I have been asked, which one of the two I would chose for two MDS >> servers (active/passive). Whether I would like to have SSDs, maybe two >> (mirrored) in both servers and DRDB for synching, or a RAID controller >> that has a 15K disks. I have not done benchmarks on this topic myself >> and would like to ask if anyone has an idea or numbers? The cluster will >> be pretty small, about 50 clients. >> >> >> Regards, Michael >> >> -- >> Dr.-Ing. Michael Kluge >> >> Technische Universität Dresden >> Center for Information Services and >> High Performance Computing (ZIH) >> D-01062 Dresden >> Germany >> >> Contact: >> Willersbau, Room WIL A 208 >> Phone: (+49) 351 463-34217 >> Fax: (+49) 351 463-37773 >> e-mail: michael.kl...@tu-dresden.de >> WWW: http://www.tu-dresden.de/zih >> _______________________________________________ >> Lustre-discuss mailing list >> Lustre-discuss@lists.lustre.org >> http://lists.lustre.org/mailman/listinfo/lustre-discuss > -- Dr.-Ing. Michael Kluge Technische Universität Dresden Center for Information Services and High Performance Computing (ZIH) D-01062 Dresden Germany Contact: Willersbau, Room WIL A 208 Phone: (+49) 351 463-34217 Fax: (+49) 351 463-37773 e-mail: michael.kl...@tu-dresden.de WWW: http://www.tu-dresden.de/zih _______________________________________________ Lustre-discuss mailing list Lustre-discuss@lists.lustre.org http://lists.lustre.org/mailman/listinfo/lustre-discuss