Bug 34138
| Summary: | Move /var/lib/xenstore/tdb on tmpfs | ||
|---|---|---|---|
| Product: | UCS | Reporter: | Philipp Hahn <hahn> |
| Component: | Virtualization - Xen | Assignee: | UCS maintainers <ucs-maintainers> |
| Status: | CLOSED WONTFIX | QA Contact: | |
| Severity: | normal | ||
| Priority: | P5 | CC: | gohmann, walkenhorst |
| Version: | UCS 3.2 | ||
| Target Milestone: | UCS 3.x | ||
| Hardware: | All | ||
| OS: | Linux | ||
| What kind of report is it?: | --- | What type of bug is this?: | --- |
| Who will be affected by this bug?: | --- | How will those affected feel about the bug?: | --- |
| User Pain: | Enterprise Customer affected?: | ||
| School Customer affected?: | ISV affected?: | ||
| Waiting Support: | Flags outvoted (downgraded) after PO Review: | ||
| Ticket number: | Bug group (optional): | Large environments, UCS Performance | |
| Max CVSS v3 score: | |||
| Bug Depends on: | 28309 | ||
| Bug Blocks: | |||
UCS-3.x is OoM. Xen is OoM. |
Ticket#: 2014021721004459 I a large Xen environment with 18 VMs running on a single host, xenstored generated so much load, that "virsh list" took ages and "virsh dumpxml $DOM" didn't return for several minutes. This is caused by xen/tools/python/xen/xend/XendDomainInfo.py # _update_consoles() 1638 # The value is unchanged. Just for xenstore watcher 1639 console_ctrl.writeBackend(0, 'uuid', console_uuid) which writes back the DB for each VM looked up. Each lookup took roughly 1 seconds, for a total of 15 seconds for all 18 VMs. As UVMMd is querying all VMs every 30 seconds, this seems to get in some kind of loop. ("virsh dumpxml $DOM" also iterates over all VMs, even wen $DOM matches the name/UUID/ID.) Putting the tdb on a tempfs solved the problem. We should do something like the following for Xen systems: echo "xenstored /var/lib/xenstored tmpfs rw,mode=755 0 0" >>/etc/fstab +++ This bug was initially created as a clone of Bug #28309 +++ The original bug only added zapping the /var/lib/xenstored/tdb file for reboots. In newer Debian the file is in /var/run/=/run/=tmpfs by default.