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Alan M. Carroll reassigned TS-3000: ----------------------------------- Assignee: Alan M. Carroll > Enable administrator control of seed strings for stripe assigment > ----------------------------------------------------------------- > > Key: TS-3000 > URL: https://issues.apache.org/jira/browse/TS-3000 > Project: Traffic Server > Issue Type: Improvement > Components: Cache > Reporter: Alan M. Carroll > Assignee: Alan M. Carroll > Fix For: 5.1.0 > > > Objects are assigned to stripes based on a hash. The seed string for this > hash is computed from properties of the storage. This means that if the > storage is changed in any way, the hashing changes which disrupts assignment > on all other stripes. > An actual example is for a deployment that uses /dev/sdb .. /dev/sdx. If one > of these disks fails (say /dev/sdm) then all of the other drives will "move > down' at the next system restart which will in turn change the hash seed > string for them which will make almost all of the cached objects on those > drives inaccessible. Losing a single drive could wipe out most of the cache. > This fix allows an administrator to specify the hash seed string in the > storage.config file. The seed strings (and hence the resulting hash) can be > kept consistent for a physical device even if the operating system assignment > is changed. > P.S. As a side note for Linux users, there are symlinks for raw disk devices > in /dev/disk. These can be used in storage.config to avoid some of these > problems. -- This message was sent by Atlassian JIRA (v6.2#6252)