Thanks for clarifying that, Gregory. As said before, we use the file layout to resolve the difference of workloads in those 2 different directories in cephfs. Would you recommend using 2 filesystems instead? By doing so, each fs would have it's default data pool accordingly.
Regards, Webert Lima DevOps Engineer at MAV Tecnologia *Belo Horizonte - Brasil* *IRC NICK - WebertRLZ* On Wed, Jun 13, 2018 at 11:33 AM Gregory Farnum <gfar...@redhat.com> wrote: > The backtrace object Zheng referred to is used only for resolving hard > links or in disaster recovery scenarios. If the default data pool isn’t > available you would stack up pending RADOS writes inside of your mds but > the rest of the system would continue unless you manage to run the mds out > of memory. > -Greg > On Wed, Jun 13, 2018 at 9:25 AM Webert de Souza Lima < > webert.b...@gmail.com> wrote: > >> Thank you Zheng. >> >> Does that mean that, when using such feature, our data integrity relies >> now on both data pools' integrity/availability? >> >> We currently use such feature in production for dovecot's index files, so >> we could store this directory on a pool of SSDs only. The main data pool is >> made of HDDs and stores the email files themselves. >> >> There ain't too many files created, it's just a few files per email user, >> and basically one directory per user's mailbox. >> Each mailbox has a index file that is updated upon every new email >> received or moved, deleted, read, etc. >> >> I think in this scenario the overhead may be acceptable for us. >> >> >> Regards, >> >> Webert Lima >> DevOps Engineer at MAV Tecnologia >> *Belo Horizonte - Brasil* >> *IRC NICK - WebertRLZ* >> >> >> On Wed, Jun 13, 2018 at 9:51 AM Yan, Zheng <uker...@gmail.com> wrote: >> >>> On Wed, Jun 13, 2018 at 3:34 AM Webert de Souza Lima >>> <webert.b...@gmail.com> wrote: >>> > >>> > hello, >>> > >>> > is there any performance impact on cephfs for using file layouts to >>> bind a specific directory in cephfs to a given pool? Of course, such pool >>> is not the default data pool for this cephfs. >>> > >>> >>> For each file, no matter which pool file data are stored, mds alway >>> create an object in the default data pool. The object in default data >>> pool is used for storing backtrace. So files stored in non-default >>> pool have extra overhead on file creation. For large file, the >>> overhead can be neglect. But for lots of small files, the overhead may >>> affect performance. >>> >>> >>> > Regards, >>> > >>> > Webert Lima >>> > DevOps Engineer at MAV Tecnologia >>> > Belo Horizonte - Brasil >>> > IRC NICK - WebertRLZ >>> > _______________________________________________ >>> > ceph-users mailing list >>> > ceph-users@lists.ceph.com >>> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >
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