[TS-4870] Storage can be marked offline multiple times which breaks related metrics

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 7.0.0
• Component/s: Cache, Metrics
• Assignee: Gancho Tenev
• Reporter: Gancho Tenev
• Created: 15/Sep/16 07:01
• Updated: 07/Nov/16 23:26
• Resolved: 20/Sep/16 17:21

Description

Let us say traffic server is running with 2 disks

$ cat etc/trafficserver/storage.config
/dev/sdb
/dev/sdc

$ sudo fdisk -l|grep 'Disk /dev/sd[b|c]'
Disk /dev/sdb: 134 MB, 134217728 bytes
Disk /dev/sdc: 134 MB, 134217728 bytes

Let us see what happens when we mark the same disk 3 times in a raw (/dev/sdb) and check the proxy.node.cache.bytes_total.

# Initial cache size (when using both disks).
$ ./bin/traffic_ctl metric get proxy.node.cache.bytes_total
proxy.node.cache.bytes_total 268025856

# Take 1st disk offline. Cache size changes as expected.
$ sudo ./bin/traffic_ctl storage offline /dev/sdb
$ ./bin/traffic_ctl metric get proxy.node.cache.bytes_total
proxy.node.cache.bytes_total 134012928

# Take same disk offline again. Not good!
$ sudo ./bin/traffic_ctl storage offline /dev/sdb
$ ./bin/traffic_ctl metric get proxy.node.cache.bytes_total
proxy.node.cache.bytes_total 0

# Take same disk offline again. Negative value.
$ sudo ./bin/traffic_ctl storage offline /dev/sdb
$ ./bin/traffic_ctl metric get proxy.node.cache.bytes_total
proxy.node.cache.bytes_total -134012928

Issue Links

• links to: GitHub Pull Request #1028