PCIe
● topology : Point-to-Point
● frequency: 2.5 GHz
● width : 2 wires per lane/per direction (Up to 32 lanes)
● Max. throughput : 500~16000 MB/sec
● Split transaction : Yes
● Dev. type: Root complex, Switches, Bridges, Endpoints
● Layer : Physical layer, Data Link layer, Transaction layer
● PCIe employs packets to accomplish data transfer between devices--
Transaction Layer Packets (TLPs)
● There are 4 types of transactions--
Memory, I/O, Configuration, Messages
● What is transactionsseries ?
series of packet transmissions to complete information exchange between
requester and completer
● Posted = Requester transmits TLP request packet, completer
does not return completion packet --> Memory Write, Message
● Non-posted = Requester transmits TLP request packet,
completer returns completion packet to requester,
May include data in the request or completion TLP
--> Memory Read, Memory Read Lock, I/O Read, I/O Write, Config Read, Config Write
Tuesday, October 26, 2010
High Availability systems under Linux
文章閱讀筆記
#
What is HA?
High Availability is what it says it is.
Something that is Highly Available.
#
The service runs on a machine, and redirecting the service and requests to another healthy machine is the art of High Availability.
#
How will this work
if master node fails, then the slave node may take over its ip address and start serving the requests.This method is called IP takeover.
#
How do clusters talk
They will talk to each other over a serial cable and over a cross link Ethernet cable (for redundancy, serial cable or Ethernet cable may fail) and check each others heartbeat.
The program to monitor the heartbeats of the cluster nodes is called... guess...heartbeat.
heartbeat is available at http://www.linux-ha.org/download/
The program for ip address take over is called fake and is integrated in heartbeat.
#
What about data integrity issues
When service httpd moves from node1 to node2 it does not see the same data. I loose all the files that I was creating with my httpd CGI's.
Two Answers:
1. You should never write to file from your CGI's. (use a network database instead.. MySQL is pretty good)
2. You can attach the two nodes to a central external SCSI storage, and make sure that only one is talking to it at one time, and also make sure that you change the SCSI id of the host card on machine a to 6 and leave on machine b 7 or vice -versa.
You can run GFS (Global File System, see below in resources) over FC which allows you to have transparent access to the storage from all machines as if they were local storage.
#
What about active/active cluster
You can easily build an Active/Active server if you have a good storage system that allows concurrent access.
Examples are Fibrechannel and GFS.
If you are content with Network filesystems such as NFS, you may use that, but I would not suggest that.
Anyway, you can map serviceA to clustnode1 and serviceB to clustnode2 example of my haresource file
clustnode2 172.23.2.13 mysql
clustnode1 172.23.2.14 ldap
clustnode2 172.23.2.15 cyrus
I use GFS for storage so I don't have a problem with concurrent access to data and can run as many services as is manageable by these machines.
Here clustnode2 is the master for mysql and cyrus which clustnode1 is the master for ldap.
If clustnode2 goes down then clustnode1 takes over all the ip addresses and the services.
#
What is HA?
High Availability is what it says it is.
Something that is Highly Available.
#
The service runs on a machine, and redirecting the service and requests to another healthy machine is the art of High Availability.
#
How will this work
if master node fails, then the slave node may take over its ip address and start serving the requests.This method is called IP takeover.
#
How do clusters talk
They will talk to each other over a serial cable and over a cross link Ethernet cable (for redundancy, serial cable or Ethernet cable may fail) and check each others heartbeat.
The program to monitor the heartbeats of the cluster nodes is called... guess...heartbeat.
heartbeat is available at http://www.linux-ha.org/download/
The program for ip address take over is called fake and is integrated in heartbeat.
#
What about data integrity issues
When service httpd moves from node1 to node2 it does not see the same data. I loose all the files that I was creating with my httpd CGI's.
Two Answers:
1. You should never write to file from your CGI's. (use a network database instead.. MySQL is pretty good)
2. You can attach the two nodes to a central external SCSI storage, and make sure that only one is talking to it at one time, and also make sure that you change the SCSI id of the host card on machine a to 6 and leave on machine b 7 or vice -versa.
You can run GFS (Global File System, see below in resources) over FC which allows you to have transparent access to the storage from all machines as if they were local storage.
#
What about active/active cluster
You can easily build an Active/Active server if you have a good storage system that allows concurrent access.
Examples are Fibrechannel and GFS.
If you are content with Network filesystems such as NFS, you may use that, but I would not suggest that.
Anyway, you can map serviceA to clustnode1 and serviceB to clustnode2 example of my haresource file
clustnode2 172.23.2.13 mysql
clustnode1 172.23.2.14 ldap
clustnode2 172.23.2.15 cyrus
I use GFS for storage so I don't have a problem with concurrent access to data and can run as many services as is manageable by these machines.
Here clustnode2 is the master for mysql and cyrus which clustnode1 is the master for ldap.
If clustnode2 goes down then clustnode1 takes over all the ip addresses and the services.
Wednesday, October 20, 2010
Advantages of Ethernet Tunneling through PCI Express
There are many advantages to tunneling Ethernet packets through PCIe, including:
1. PCIe has higher bandwidth than Ethernet (64 Gbps today vs. 10 Gbps);
2. PCIe has lower latency compared to any other protocol;
3. PCIe has the lowest per port pricing (1/10) compared to any higher-level protocol;
4. Ethernet tunneling saves power and cost; and
5. Ethernet tunneling uses the same software stack protecting software investment.
These advantages are compelling.
以上文字擷取自以下網址
http://www.wwpi.com/index.php?option=com_content&view=article&id=6540:ethernet-tunneling-through-pci-express-inter-processor-communication-low-latency-storage-io&catid=99:cover-story&Itemid=2701018
1. PCIe has higher bandwidth than Ethernet (64 Gbps today vs. 10 Gbps);
2. PCIe has lower latency compared to any other protocol;
3. PCIe has the lowest per port pricing (1/10) compared to any higher-level protocol;
4. Ethernet tunneling saves power and cost; and
5. Ethernet tunneling uses the same software stack protecting software investment.
These advantages are compelling.
以上文字擷取自以下網址
http://www.wwpi.com/index.php?option=com_content&view=article&id=6540:ethernet-tunneling-through-pci-express-inter-processor-communication-low-latency-storage-io&catid=99:cover-story&Itemid=2701018
Subscribe to:
Posts (Atom)