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https://issues.apache.org/jira/browse/TS-2384?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Igor Galić updated TS-2384:
---------------------------
Description:
As reported on users@
{noformat}
ATS 4.0.1
Volume #1 - store='/dev/sda'
first key 409542BD429764BEE60B0610B8924C4D
key 6BA7E5696E9A9E7A1E05212E5264D3C4
sync_serial 10836
write_serial 388912
header length 2480
fragment type 1
No of Alternates 1
{noformat}
{noformat}
ATS 4.1.1
Volume #1 - store='/dev/sda'
first key 409542BD429764BEE60B0610B8924C4D
key 34CEA58AC5FBA6D240C484307DE4C315
sync_serial 10837
write_serial 388912
header length 2480
fragment type 1
No of Alternates 1
{noformat}
When run 4.1.1 all previously cached objects under 4.0.1 are MISS, these
objects downloading from parent, and then they HIT again.
*Note* This does not cause the cache to be reinitialized.
It's just that the generated cache-lookup *key* is wrong in 4.1.x. This means
that the existing objects on the disks will stay in place, but we won't be able
to find them, because we are looking in the wrong place. As such we simply
store the object again.
That's *almost* the same for people running with a 60 TiB cache, because
everything requested is also stored again,
and after a while the old objects that have been lying around for a while will
be rotated out so that's bad. People with
tiny caches or very high turn overs might even notice the downward spike in
304s.
was:
As reported on users@
{noformat}
ATS 4.0.1
Volume #1 - store='/dev/sda'
first key 409542BD429764BEE60B0610B8924C4D
key 6BA7E5696E9A9E7A1E05212E5264D3C4
sync_serial 10836
write_serial 388912
header length 2480
fragment type 1
No of Alternates 1
{noformat}
{noformat}
ATS 4.1.1
Volume #1 - store='/dev/sda'
first key 409542BD429764BEE60B0610B8924C4D
key 34CEA58AC5FBA6D240C484307DE4C315
sync_serial 10837
write_serial 388912
header length 2480
fragment type 1
No of Alternates 1
{noformat}
When run 4.1.1 all previously cached objects under 4.0.1 are MISS, these
objects downloading from parent, and then they HIT again.
> Regression in key-lookup code between 4.0.x and 4.1.x
> -----------------------------------------------------
>
> Key: TS-2384
> URL: https://issues.apache.org/jira/browse/TS-2384
> Project: Traffic Server
> Issue Type: Bug
> Components: Cache
> Reporter: Igor Galić
> Fix For: 4.1.2
>
>
> As reported on users@
> {noformat}
> ATS 4.0.1
> Volume #1 - store='/dev/sda'
> first key 409542BD429764BEE60B0610B8924C4D
> key 6BA7E5696E9A9E7A1E05212E5264D3C4
> sync_serial 10836
> write_serial 388912
> header length 2480
> fragment type 1
> No of Alternates 1
> {noformat}
> {noformat}
> ATS 4.1.1
> Volume #1 - store='/dev/sda'
> first key 409542BD429764BEE60B0610B8924C4D
> key 34CEA58AC5FBA6D240C484307DE4C315
> sync_serial 10837
> write_serial 388912
> header length 2480
> fragment type 1
> No of Alternates 1
> {noformat}
> When run 4.1.1 all previously cached objects under 4.0.1 are MISS, these
> objects downloading from parent, and then they HIT again.
> *Note* This does not cause the cache to be reinitialized.
> It's just that the generated cache-lookup *key* is wrong in 4.1.x. This means
> that the existing objects on the disks will stay in place, but we won't be
> able to find them, because we are looking in the wrong place. As such we
> simply store the object again.
> That's *almost* the same for people running with a 60 TiB cache, because
> everything requested is also stored again,
> and after a while the old objects that have been lying around for a while
> will be rotated out so that's bad. People with
> tiny caches or very high turn overs might even notice the downward spike in
> 304s.
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