Skip to main content

Enable Fast I/O Failure for FC adapt

AIX 5.2 supports the Fast I/O Failure feature for Fibre Channel devices in case of link events in a switched environment. If the FC adapter driver detects a link event (for example, a lost link between a storage device and a switch), the FC adapter driver waits a short period of time, about 15 seconds, to allow the SAN fabric to stabilize. At this point, if the FC adapter driver detects that the device is not on the SAN fabric, it begins failing all I/O requests at the adapter driver level. Any new I/O request, or future retries of the previously failed I/Os, are failed immediately by the adapter, until the adapter driver detects that the device has rejoined the SAN fabric.


Fast I/O Failure is controlled by a new fscsi device attribute, fc_err_recov. The default setting for this attribute is delayed_fail, which is the I/O failure behavior that has existed in previous versions of AIX. Setting this attribute to fast_fail enables Fast I/O Failure, as shown in Example 3-12.

Example 3-12 FC adapter fast_fail option

{node1:root}/_> chdev -l fscsi0 -a fc_err_recov=fast_fail

The fscsi0 device is used for storage data transfer and is a child device of fcs0 (the FC adapter):

+ fcs0 U0.1-P1-I4/Q1 FC Adapter* fscsi0 U0.1-P1-I4/Q1 FC SCSI I/O Controller Protocol DeviceFast fail logic is invoked when the adapter driver receives an indication from the switch that there has been a link event involving a remote storage device port via a Registered State Change Notification (RSCN) from the switch.

Fast I/O Failure may be desirable in situations where multipath software is being used. Setting fc_err_recov to fast_fail may decrease the I/O fail times due to link loss between the storage device and switch and allow faster failover to alternate paths.

In single-path configurations, especially in configurations with a single path to a paging device, the default delayed_fail setting is recommended.

Fast I/O Failure is only supported in a switched environment. It is not supported in arbitrated loop environments, including public loop.

We configured Fast I/O Failure since we were using the Subsystem Device Driver, two adapters per node and two paths to the storage subsystem.

The requirements for Fast I/O Failure support are the following:

FC 6227 adapter firmware - level 3.22A1 or greater

FC 6228 adapter firmware - level 3.82A1 or greater

FC 6239 adapter firmware - all firmware levels

Comments

Post a Comment

Popular posts from this blog

ipsec tunnel pfSense and Centos

pfSense 1.2.3 -------- external ip: 1.1.1.1 internal ip: 172.20.1.20 internal network: 172.20.1.0/24 Centos 5.5 -------- external ip: 2.2.2.2 internal ip: 172.20.2.1 internal network: 172.20.2.0/24 pfSense config from a reset. Firewall rule to allow all ipsec communication (all protocols). pfSense ipsec config -------------------- Mode: Tunnel Interface: WAN (I'm not sure this should be WAN, but changing it to LAN makes no difference) Local subnet: 172.20.1.0/24 Remote subnet: 172.20.2.0/24 Remote gateway: 2.2.2.2 Phase 1 Negotiation mode: agressive My identifier: My IP adress Encryption algorithm: 3DES Hash algorithm: SHA1 DH key group: 2 Authentication method: Pre-shared key Pre-Shared Key: secret Phase 2 Protocol: ESP Encryption algorithms: Rijndael (AES) Hash algorithms: SHA1 PFS key group: 2   Centos ipsec config ------------------- /etc/sysconfig/network-scripts/ifcfg-ipsec0 TYPE=IPSEC ...
1 comment
Read more

Endian Firewall

With perilous threats from crackers and script kiddes lurking in the network, IT administrators could do no better than placing a firewall protection. Firewall prevents unwanted access to departmental systems while preventing local systems from attacking systems on the other network. It ensures that the traffic entering and leaving the secured LAN is accessing the correct applications on the correct computers. We had already done with the top free Windows firewall. However, there is cool open source firewall to take advantage of. Open source firewall not only offers better customization options, but also reduces the cost of ownership. After a comprehensive search we assorted the top 10 open source firewall. 1. Endian Firewall This is an open source firewall based on the IPCop Linux Firewall. It is one of the most widely used open source firewall with comprehensive features. It is almost an opensource Universal threat Management (UTM) device with a Statefull firewall, VPN, Webpro...
Post a Comment
Read more

Typical Oracle RAC configurations

All configurations are based on the following building blocks: Hardware Server nodes Storage Networking Software Operating system Cluster software Oracle RAC (application) Application architecture Oracle9i RAC on RAW devices is based on a shared disk architecture. Figure 2-1 shows a two-node cluster. The lower solid line is the primary Oracle interconnect, the middle dashed line is the secondary Oracle interconnect. For high availability, both these networks should be defined in the HACMP as "private". HACMP/ESCRM provides Oracle9i RAC with the infrastructure for concurrent access to disks. Although HACMP provides concurrent access and a disk locking mechanism, this mechanism is not used. Oracle, instead, provides its own locking mechanism for concurrent data access, integrity, and consistency. Volume groups are varied on all the nodes, thus ensuring short failover time. This type of concurrent access can only be provided for RAW ...
Post a Comment
Read more