Changes between Version 2 and Version 3 of FAQ/GNBD


Ignore:
Timestamp:
05/21/11 18:25:43 (3 years ago)
Author:
digimer
Comment:

Fixed the last copy from the old wiki to work on the new Trac syntax.

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  • FAQ/GNBD

    v2 v3  
    88 * [#gnbd_vs_iscsi What are the advantages/disadvantages to using GNBD versus iSCSI for exporting storage in a cluster?] 
    99 
    10 [[Anchor(gnbd_what)]] 
    11 ==== What is GNBD and when do I need it? ==== 
     10==== What is GNBD and when do I need it? ==== #gnbd_what 
    1211GNBD is a kernel module that lets you export any block device from one node to another. 
    1312You don't need it for normal cluster operations, but you can do some cool things with it. 
    1413 
    15 [[Anchor(gnbd_importing)]] 
    16 ==== How do I import GNBDs? ==== 
     14==== How do I import GNBDs? ==== #gnbd_importing 
    1715You modprobe gnbd, and then run `gnbd_import -i <server_name>` 
    1816The gnbd export name must be cluster unique. So you cannot export a GNBD named "foo" 
    1917from serverA and serverB.  You need to have both gnbd devices imported. 
    2018 
    21 [[Anchor(gnbd_inconf)]] 
    22 ==== Do the client machines have to be in cluster.conf? ==== 
     19==== Do the client machines have to be in cluster.conf? ==== #gnbd_inconf 
    2320Yes.  When you have Fibre Channel attached storage, you are get a new sd* device for every path to 
    2421the storage device.  Multipath takes all these devices and makes one multipathed device 
     
    3330Otherwise half you data will end up on one device, and half your data will end up on another device. 
    3431 
    35 [[Anchor(gnbd_multipath)]] 
    36 ==== Do I need something special in multipath.conf to work with GNBD? ==== 
     32==== Do I need something special in multipath.conf to work with GNBD? ==== #gnbd_multipath 
    3733No.  GNBD devices should work correctly by using defaults. 
    3834 
    3935See the gnbd_export man page for more information. 
    4036 
    41 [[Anchor(gnbd_firewall)]] 
    42 ==== What ports should be enabled in the iptables firewall to allow gnbd? ==== 
     37==== What ports should be enabled in the iptables firewall to allow gnbd? ==== #gnbd_firewall 
    4338You need to enable port 14567 (tcp). 
    4439 
    45 [[Anchor(gnbd_dash_u)]] 
    46 ==== Should I use -U or -u for gnbd_export? ==== 
     40==== Should I use -U or -u for gnbd_export? ==== #gnbd_dash_u 
    4741In almost all cases, you should use -U (capital U) not -u. 
    4842The -U option specifies a uuid callout command.  You can specify -U<command> 
     
    5246wrong with multipathing, you can cause data corruption. 
    5347 
    54 [[Anchor(gnbd_vs_iscsi)]] 
    55 ==== What are the advantages/disadvantages to using GNBD versus iSCSI for exporting storage in a cluster? ==== 
     48==== What are the advantages/disadvantages to using GNBD versus iSCSI for exporting storage in a cluster? ==== #gnbd_vs_iscsi 
    5649The only real advantage of using GNBD is that it has built in fencing. With 
    5750iSCSI, you still need some somthing to fence all the machines (unless your scsi