We avoid putting more than one piece of a segment on the same /24
network (or /64 for ipv6). However, it is possible for multiple pieces
of the same segment to move to the same network over time. Nodes can
change addresses, or segments could be uploaded with dev settings, etc.
We will call such pieces "clumped", as they are clumped into the same
net, and are much more likely to be lost or preserved together.
This change teaches the repair checker to recognize segments which have
clumped pieces, and put them in the repair queue. It also teaches the
repair worker to repair such segments (treating clumped pieces as
"retrievable but unhealthy"; i.e., they will be replaced on new nodes if
possible).
Refs: https://github.com/storj/storj/issues/5391
Change-Id: Iaa9e339fee8f80f4ad39895438e9f18606338908
It looks that monikt monitoring can give high CPU overhead for
segments loop observer. With this code we are changing how monitoring
is initialized for observer methods. This optimization affects mainly
path where segment is healthy and doesn't require repair. Benchmark
is also added to show difference between old and new approach.
Benchmark against 'main':
name old time/op new time/op delta
RemoteSegment/Cockroach/healthy_segment-8 8.55µs ± 4% 1.37µs ± 6% -84.03% (p=0.008 n=5+5)
name old alloc/op new alloc/op delta
RemoteSegment/Cockroach/healthy_segment-8 2.63kB ± 0% 0.17kB ± 0% -93.62% (p=0.008 n=5+5)
name old allocs/op new allocs/op delta
RemoteSegment/Cockroach/healthy_segment-8 54.0 ± 0% 8.0 ± 0% -85.19% (p=0.008 n=5+5)
Change-Id: Ie138eab0d59e436395b13f57bdfb11f9871d4c18
We made optimization for segment loop observers to avoid
heavy monkit initialization on each call. It was applied to very
often executed methods. Unfortunately we used wrong monkit
method to track function times. Instead mon.Task we used
mon.Func().
https://github.com/spacemonkeygo/monkit#how-it-works
Change-Id: I9ca454dbd828c6b43ba09ca75c341991d2fd73a8
Recently we applied this optimization to metrics observer and time
used by its method dropped from 12m to 3m for us1 (220m segments).
It looks that it make sense to apply the same code to all observers.
Change-Id: I05898aaacbd9bcdf21babc7be9955da1db57bdf2
This change adds a NOT NULL constraint to the created_at column in the segment table.
All occurrences of CreatedAt as a pointer are changed to non pointer version (metabase, segment loop, etc)
Change-Id: I3efd476ebd1edd3327b69c9223d9edc800e1cc52
Error from joining loop should not restart satellite. This will be the
same error like for loop itself. In the same way we are handling joining
error for other services that are using segment loop.
Change-Id: Idf1035ef7f78462927bd23989ed8a4ee5826c49e
We want to use StreamID/Position to identify injured
segment. As it is hard to alter existing injuredsegments
table we are adding a new table that will replace existing
one. Old table will be dropped later.
Change-Id: I0d3b06522645013178b6678c19378ebafe485c49
This is part of metaloop refactoring. We plan to remove
irreparable at some point but there was not time for it.
Now instead refatoring it for segmentloop its just easier
to drop it.
Later we still need to drop table with migration step.
Change-Id: I270e77f119273d39a1ecdcf5e1c37a5662a29ab4
Currently the interface is not useful. When we need to vary the
implementation for testing purposes we can introduce a local interface
for the service/chore that needs it, rather than using the large api.
Unfortunately, this requires adding a cleanup callback for tests, there
might be a better solution to this problem.
Change-Id: I079fe4dbe297b0ae08c10081a1cea4dfbc277682
errs.Class should not contain "error" in the name, since that causes a
lot of stutter in the error logs. As an example a log line could end up
looking like:
ERROR node stats service error: satellitedbs error: node stats database error: no rows
Whereas something like:
ERROR nodestats service: satellitedbs: nodestatsdb: no rows
Would contain all the necessary information without the stutter.
Change-Id: I7b7cb7e592ebab4bcfadc1eef11122584d2b20e0
Currently the loop handling is heavily related to the metabase rather
than metainfo.
metainfo over time has become related to the "public API" for accessing
the metabase data.
Currently updates monkit.lock, because monkit monitoring does not handle
ScopeNamed correctly. Needs a followup change to monitoring check.
Change-Id: Ie50519991d718dfb872ec9a0176a82e732c97584
metabase has become a central concept and it's more suitable for it to
be directly nested under satellite rather than being part of metainfo.
metainfo is going to be the "endpoint" logic for handling requests.
Change-Id: I53770d6761ac1e9a1283b5aa68f471b21e784198
Check that the bloom filter creation date is earlier than the
metainfo loop system time used for db scanning.
Change-Id: Ib0f47c124f5651deae0fd7e7996abcdcaac98fb4
Repair checker expects to have information about CreatedAt and RepairedAt fields to calculate segment age metric.
Change-Id: I6b41df880d77133be541e14d10d91cc75759b339
We have multipart objects so we may get multiple inline segments
sequences or no segments at all for objects.
Change-Id: Ie46ee777a2db8f18f7154e3443bb9e07ecb170f7
Do not insert the number of healthy pieces for segment health anymore.
Rather, insert the segment health calculated by our new priority
function.
Change-Id: Ieee7fb2deee89f4d79ae85bac7f577befa2a0c7f
The chief segment health models we've come up with are the "immediate
danger" model and the "survivability" model. The former calculates the
chance of losing a segment becoming lost in the next time period (using
the CDF of the binomial distribution to estimate the chance of x nodes
failing in that period), while the latter estimates the number of
iterations for which a segment can be expected to survive (using the
mean of the negative binomial distribution). The immediate danger model
was a promising one for comparing segment health across segments with
different RS parameters, as it is more precisely what we want to
prevent, but it turns out that practically all segments in production
have infinite health, as the chance of losing segments with any
reasonable estimate of node failure rate is smaller than DBL_EPSILON,
the smallest possible difference from 1.0 representable in a float64
(about 1e-16).
Leaving aside the wisdom of worrying about the repair of segments that
have less than a 1e-16 chance of being lost, we want to be extremely
conservative and proactive in our repair efforts, and the health of the
segments we have been repairing thus far also evaluates to infinity
under the immediate danger model. Thus, we find ourselves reaching for
an alternative.
Dr. Ben saves the day: the survivability model is a reasonably close
approximation of the immediate danger model, and even better, it is
far simpler to calculate and yields manageable values for real-world
segments. The downside to it is that it requires as input an estimate
of the total number of active nodes.
This change replaces the segment health calculation to use the
survivability model, and reinstates the call to SegmentHealth() where it
was reverted. It gets estimates for the total number of active nodes by
leveraging the reliability cache.
Change-Id: Ia5d9b9031b9f6cf0fa7b9005a7011609415527dc
A few weeks ago it was discovered that the segment health function
was not working as expected with production values. As a bandaid,
we decided to insert the number of healthy pieces into the segment
health column. This should have effectively reverted our means of
prioritizing repair to the previous implementation.
However, it turns out that the bandaid was placed into the code which
removes items from the irreparable db and inserts them into the repair
queue.
This change: insert number of healthy pieces into the repair queue in the
method, RemoteSegment
Change-Id: Iabfc7984df0a928066b69e9aecb6f615253f1ad2
There is a new checker field called statsCollector. This contains
a map of stats pointers where the key is a stringified redundancy
scheme. stats contains all tagged monkit metrics. These metrics exist
under the key name, "tagged_repair_stats", which is tagged with the
name of each metric and a corresponding rs scheme.
As the metainfo observer works on a segment, it checks statsCollector
for a stats corresponding to the segment's redundancy scheme. If one
doesn't exist, it is created and chained to the monkit scope. Now we can call
Observe, Inc, etc on the fields just like before, and they have tags!
durabilityStats has also been renamed to aggregateStats.
At the end of the metainfo loop, we insert the aggregateStats totals into the
corresponding stats fields for metric reporting.
Change-Id: I8aa1918351d246a8ef818b9712ed4cb39d1ea9c6
We did not test the SegmentHealth function with actual production
values, and it turns out that values such as 52 healthy, 35 minimum
result in +Inf segment health - so pretty much all segments put into the
repair queue have the same health, which means we effectively aren't
sorting by health.
This change inserts numHealthy as segment health into the database so
the segments are ordered as they were before. We need to refine the
SegmentHealth function before we can support multi RS.
Change-Id: Ief19bbfee3594c5dfe94ca606bc930f05f85ff74
Rather than having a single repair override value, we will now support
repair override values based on a particular segment's RS scheme.
The new format for RS override values is
"k/o/n-override,k/o/n-override..."
Change-Id: Ieb422638446ef3a9357d59b2d279ee941367604d
We plan to add support for a new Reed-Solomon scheme soon, but our
repair queue orders segments by least number of healthy pieces first.
With a second RS scheme, fewer healthy pieces will not necessarily
correlate to lower health.
This change just adds the new column in a migration. A separate change
will add the new health function.
Right now, since we only support one RS scheme, behavior will not
change. Number of healthy pieces is being inserted as "segment health"
until the new health function is merged.
Segment health is calculated with a new priority function created in
commit 3e5640359. In order to use the function, a new config value is
added, called NodeFailureRate, representing the approximate probability
of any individual node going down in the duration of one checker run.
Change-Id: I51c4202203faf52528d923befbe886dbf86d02f2
The current monkit reporting for "remote_segments_lost" is not usable for
triggering alerts, as it has reported no data. To allow alerting, two new
metrics "checker_segments_below_min_req" and "repairer_segments_below_min_req"
will increment by zero on each segment unless it is below the minimum
required piece count. The two metrics report what is found by the checker
and the repairer respectively.
Change-Id: I98a68bb189eaf68a833d25cf5db9e68df535b9d7
A change was made to use a metabase.SegmentKey (a byte slice alias)
as the last seen item to iterate through the irreparable DB in a
for loop. However, this SegmentKey was not initialized, thus it was
nil. This caused the DB query to return nothing, and healthy segments
could not be cleaned out of the irreparable DB.
Change-Id: Idb30d6fef6113a30a27158d548f62c7443e65a81
As part of the Metainfo Refactoring, we need to make the Metainfo Loop
working with both the current PointerDB and the new Metabase. Thus, the
Metainfo Loop should pass to the Observer interface more specific Object
and Segment types instead of pb.Pointer.
After this change, there are still a couple of use cases that require
access to the pb.Pointer (hence we have it as a field in the
metainfo.Segment type):
1. Expired Deletion Service
2. Repair Service
It would require additional refactoring in these two services before we
are able to clean this.
Change-Id: Ib3eb6b7507ed89d5ba745ffbb6b37524ef10ed9f
Repair workers prioritize the most unhealthy segments. This has the consequence that when we
finally begin to reach the end of the queue, a good portion of the remaining segments are
healthy again as their nodes have come back online. This makes it appear that there are more
injured segments than there actually are.
solution:
Any time the checker observes an injured segment it inserts it into the repair queue or
updates it if it already exists. Therefore, we can determine which segments are no longer
injured if they were not inserted or updated by the last checker iteration. To do this we
add a new column to the injured segments table, updated_at, which is set to the current time
when a segment is inserted or updated. At the end of the checker iteration, we can delete any
items where updated_at < checker start.
Change-Id: I76a98487a4a845fab2fbc677638a732a95057a94
Another change which is a part of refactoring to replace path parameter
(string/[]byte) with key paramter (metabase.SegmentKey)
Change-Id: I617878442442e5d59bbe5c995f913c3c93c16928
* add monkit stat new_remote_segments_needing_repair, which reports the
number of new unhealthy segments in the repair queue since the previous
checker iteration
Change-Id: I2f10266006fdd6406ece50f4759b91382059dcc3
