Aeron Manual

[Florence Rocle]

MyReplayMerge gets stuck in state ATTEMPT_LIVE_JOIN, then times out due to no progress. It adds the live destination with no issues (I see the corresponding subscription appear in aeron-stat and the onImageAvailable callback is invoked). Eventually it catches up fully but doesn't transition to the next state.

After an investigation, I found that the problematic check is in function shouldStopAndRemoveReplay where image.activeTransportCount() >= 2 is false because image.activeTransportCount() stays at 1. If it weren't for that check the ReplayMerge would succeed.

The second one is from the added liveDestination. Once created it doesn't catch up at all, contrary to my initial assessment above. sub-pos and rcv-pos are stuck at the initial position of 452971520, but the rcv-hwm goes up together with the position of the replay subscription. Doesn't this indicate that data is being received but not read on the live destination subscription?

so that the session ID of the replay channel is set to be that of the Publication associated to tag PUBLICATION_TAG. This works as well in the case where the publishing media driver and subscribing media driver are distinct but you still have to somehow communicate the Publication tag to the subscriber which might be inconvenient.

So the solution I'll be going for is to take the session ID from the recording descriptor of the recording to be replayed, at the earlier point where I discover recordings with AeronArchive#listRecordingsForUri (or similar).

Both Publications and Subscriptions in Aeron can support the concept of multiple simultaneous destinations. For Publications, this means the outgoing stream is sent to each destination individually. For subscriptions, this means the incoming stream(s) may be received by a number of individual endpoints.

Aeron Publications can be configured to operate in a multiple destination mode separate from UDP multicast. Whereas multicast sends to an IP multicast address, Multi-Destination-Cast (MDC) sends a UDP unicast stream to each Receiver individually. This behaviour mimics UDP multicast operation for purposes of Flow and Congestion Control. Each destination is treated as a normal multicast receiver would be handled with respect to flow and congestion control.

In dynamic control mode, the Publication uses a control address, see Channel Configuration, to specify the address and port that the publication will use for receiving Status Messages and NAKs, as well as be the point of contact for the Publication to add and remove destinations dynamically. Multi-Destination-Cast dynamic publication using control port of 40456.

The Subscriptions will need to specify this control address and port, in addition to their own endpoint address. Multi-Destination-Cast dynamic subscription using local endpoint port of 40457 and control port at 192.168.0.1 and port 40456

In control-mode=manual operation. The user application calls Publication.addDestination(endpoint) to add specific destination endpoints, and removes them explicitly with Publication.removeDestination(endpoint). Multi-Destination-Cast manual publication using control port of 40456.

The destination channel used with Publication.addDestination(endpoint) and Publication.removeDestination(endpoint) should only include endpoint specification. All else will be ignored. Below is an example of adding a subscription endpoint at localhost and port 30567.

In order for another Subscription to share the same driver Subscription, Tags may be used. If multiple client Subscriptions map to the same driver Subscription, then any adding or removing of destinations is shared by all client instances.

Once a Subscription has been created that allows manual control of destinations, the API methods Subscription.addDestination(endpoint) and Subscription.removeDestination(endpoint) may be used to add and remove specific destination endpoints for the Subscription to listen on. These endpoints follow the normal channel rules for operation. It is possible for a Subscription to mix, UDP unicast, UDP multicast, and dynamic/manual MDC endpoints as desired.

MDS subscriptions can be session-specific to reduce the scope of joined images. In this case the session-id param is added to the subscription and not to each of the destinations. If a session-id param is added to a destination then it is ignored.

Channels, Publications, and Subscriptions may be tagged with 64-bit integers and referenced later. A tag is specified by the parameter tags. The value may be of two forms. A single value indicates the channel identifier tag, e.g. tags=1001 refers to tag 1001 for a channel. A double value separated by a comma indicates the channel tag and the Subscription, or Publication, tag. e.g. tags=1001,105 refers to tag 1001 for channel and a tag 105 for identifying a Publication or Subscription.

Since the problem I was having was with the recline mechanism, I traced the cables from the levers. They disappear into that formless box underneath the seat. After some wriggling around, I decided I needed to remove the seat to get better access to it.

Much of the chair is held together with allen-head bolts, so having a good set of standard-sized allen wrenches is required. Remove the two bolts from the sides of the pan, and remove the two bolts at the end of the arms under the mechanism box. They came out easily for me, but they were obviously snugged in. Once those bolts are out, pull the seat out and set it aside.

Hi!

I found your post to be very helpful and informative. I am currently trying to upgrade my basic aeron to a highly adjustable one by adding on the tilt limiter and forward tilt knobs. Based on your knowledge, would it be difficult to add in those components into the base? If so, could you give me a few pointers on how I would be able to do that? Thanks

Great walkthrough!

I have a slightly different problem with my new Aeron. The thing is that I prefer to sit straight up when working. When I use the STOP tilt to lock backward tilt, it still moves back a bit and does not stay in the straight position it is in normally. Can you tell me which screw I need to adjust this?

Thanks in advance for your help!

I also tightened the tension screw on the inside of the left arm that holds the front and rear tilt limiter cables. Models vary, so searching for schematics online before working on your chair is advisable. I hope that this helped.

Hi, any ideas? My aeron chair seat dropped below me, I needed to replace Classic Hip Pivot Bolt (MK2), I purchased but removing the old one has become a nightmare. The allen threads are damaged so I had to use a screw/bolt removal part, but there is not enough torque on my drill to remove the bolt. I bought a monkey wrench and Waterpump Pliers , but neither would remove the bolt, I used a blow torch to get through the plastic to the metal casing screw as the wrench merely twisted the outer casing. now I am down to the inner metal bolt but there is no leverage to turn the bolt.

After 4 days I am ready to put in the trash unless someone can advise! ?

Aeron Cluster allows a limited number of cluster clients to connect simultaneously (10 is the default). While you can override the base limit, care must be taken note to overload the Consensus Module with too many cluster clients.

Note that there can be situations when the count is seemingly higher than possible. For example, if you have 20 clients connected, and set the aeron.cluster.max.sessions to 20, and you have a client timeout. If the cluster client reconnects before being removed from the internal cluster sessions map, then you will receive a concurrent session limit error message. To be safe, set it slightly higher than the actual number of clients expected to connect.

Wow, great post! Thanks for this detail (I'm an engineer and love this level of detail). I have one of the newer Aerons with the new style flip lock arm rests, and they continuously become loose. I was actually hoping to find the thumbwheel style of arm rest and retrofit the body of my chair with the thumbwheel arm rest. Do you know if they are 100% compatible if I get the entire thumbwheel arm rest assembly? Also, do you know if there were major design flaws with the thumbwheel that made them move to the flip lock arm rests? To me, it seems like a backward step, given that the flip locks loosen on their own so readily. Thanks!

-JB

JB,

I can't say for certain - I did have access to a flip lock chair briefly and I seemed to remember the thumb lock arm fitting in the groove which belongs to the chairs frame. The problem was trying to remove the flip lock arm.

As for the change to flip lock.. I'm guessing it could be cost cutting/simplification as the screw lock arms have a lot of bits to them (see the exploded view in the post) where as the flip lock mechanism would have fewer.

Great write up, thanks! Got my hands on a secondhand aeron but need replacement screws to attach the seat back. Would you happen to know if any 5mm bolts work? Need to be any specific type? Thanks again!

There is a reason Herman Miller Aeron is one of the most recognized brands in ergonomic office chairs. It is comfortable, ergonomic, environmentally friendly chair for every body type. However, the Aeron chair is expensive. So to get the most out of your chair, it makes sense to upgrade/repair it with replacement Aeron chair parts. Here are the 7 commonly replaced Herman Miller Aeron chair parts list:

Office chair casters are the most replaced (or upgraded) Herman Miller Aeron chair parts. The stock aeron chair wheels will see lots of wear and tear only after a few years of use. This will cause the plastic chair casters to eventually break-down and prevent smooth rolling. If enough wear takes place you might even risk damaging your floors.

Instead of simply replacing your wheels with OEM herman miller replacement casters, it is best to consider an upgrade. The traditional "twin-wheel" casters allow your chair to move, but they have many limitations. Standard OEM Aeron casters can cause damage to hardwood floors, get tangled with hair and debris, and break after only a few years.

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