On 10/02/15 20:40, Thomas Güttler wrote:
Hi, does the lack of a battery backed cache in Ceph introduce any disadvantages? We use PostgreSQL and our servers have UPS. But I want to survive a power outage, although it is unlikely. But "hope is not an option ..."
You can certainly make use of adapter cards that have a battery backed cache with Ceph - either using RAID as usual or creating arrays of "RAID 0 of 1 disk" that enable you to use the nice battery backed cache + writeback options on the card and still have a "1 osd mapped to 1 disk" topology.
Without such cards it is still quite possible to have a power loss safe setup. These days (with reasonably modern 3.* kernels) using SATA or SAS plus mount options that do *not* disable write barriers will leave you with a consistent, safe state in the advent of power loss. You might want to test your SATA disk of choice to be sure, but SAS should be safe!
Cheers Mark _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
