Hi, To me: 12 OSTs x 1.2 GB = 14.4 GB < 16GB
So you are clearly in the recommendation. Cheers, Sebastien. Ms. Megan Larko a écrit : > Responding to what Sebastien has written: >> Hi, > >> Just a small feedback from our own experience. >> I agree with Brian about the fact that there is no strong limit on the >> number of OSTs per OSS in the Lustre code. But one should really take >> into account the available memory on OSSes when defining the number of >> OSTs per OSS (and so the size of each OST). If you do not have 1GB or >> 1.2 GB of memory per OST on your OSSes, you will run into serious > t>rouble with "out of memory" messages. > >> For instance, if you want 8 OSTs per OSS, your OSSes should have at >> least 10GB of RAM. > >> Unfortunately we experienced those "out of memory" problems, so I advise >> you to read Lustre Operations Manual chapter 33.12 "OSS RAM Size for a >> Single OST". > >> Cheers, >> Sebastien. > > We have one OSS running Lustre 2.6.18-53.1.13.el5_lustre.1.6.4.3smp. > This OSS has 16Gb RAM for 76Tb of formatted Lustre disk space. > > [r...@oss4 ~]# cat /proc/meminfo > MemTotal: 16439360 kB > MemFree: 88204 kB > > Client sees: ic-m...@o2ib:/crew8 Total Usable Space 76Tb > > The OSS has 6 JBODS, each of which is partitioned in two parts to stay > below the Lustre 8Tb per partition limit. > /dev/sdb1 6.3T 3.8T 2.3T 63% /srv/lustre/OST/crew8-OST0000 > /dev/sdb2 6.3T 3.7T 2.3T 62% /srv/lustre/OST/crew8-OST0001 > /dev/sdc1 6.3T 3.8T 2.3T 63% /srv/lustre/OST/crew8-OST0002 > /dev/sdc2 6.3T 3.8T 2.2T 64% /srv/lustre/OST/crew8-OST0003 > /dev/sdd1 6.3T 3.8T 2.2T 64% /srv/lustre/OST/crew8-OST0004 > /dev/sdd2 6.3T 4.2T 1.8T 70% /srv/lustre/OST/crew8-OST0005 > /dev/sdi1 6.3T 4.3T 1.8T 71% /srv/lustre/OST/crew8-OST0006 > /dev/sdi2 6.3T 3.8T 2.2T 64% /srv/lustre/OST/crew8-OST0007 > /dev/sdj1 6.3T 3.8T 2.3T 63% /srv/lustre/OST/crew8-OST0008 > /dev/sdj2 6.3T 3.8T 2.2T 63% /srv/lustre/OST/crew8-OST0009 > /dev/sdk1 6.3T 3.7T 2.3T 62% /srv/lustre/OST/crew8-OST0010 > /dev/sdk2 6.3T 3.7T 2.3T 63% /srv/lustre/OST/crew8-OST0011 > > As you can see, this is no where near the recommendation of 1Gb of RAM > per OST. Yes, we do occasionally, under load, see kernel panics due > to, we believe, insufficient memory and swap. These panics occur > approximately once per month. We also see watchdog messages stating > "swap page allocation failure" messages sometimes a day prior to > kernel panic. After this Lustre disk was up and running was I then > enlightened that this was too much load for a single OSS. Ah well, > live and learn. I am planning to split this one large group across > two OSSes in the next month. Hopefully the kernel panics and > watchdog errors will go away with the disk OST load shared across two > OSS machines. > > Just one real life scenario for your consideration. > > megan > _______________________________________________ > 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
