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Lines 24-30
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.\" |
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.\" |
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.\" $FreeBSD$ |
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.\" $FreeBSD$ |
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.\" |
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.\" |
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.Dd April 18, 2012 |
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.Dd April 5, 2015 |
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.Dt GMULTIPATH 8 |
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.Dt GMULTIPATH 8 |
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.Os |
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.Os |
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.Sh NAME |
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.Sh NAME |
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Lines 253-266
This I/O continues until an I/O is returned with
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| 253 |
a generic I/O error or a "Nonexistent Device" error. |
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a generic I/O error or a "Nonexistent Device" error. |
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When this occurs, that path is marked FAIL, the next path |
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When this occurs, that path is marked FAIL, the next path |
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in a list is selected as active and the failed I/O reissued. |
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in a list is selected as active and the failed I/O reissued. |
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In Active/Active mode all paths not marked FAIL may handle I/O same time. |
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In Active/Active mode all paths not marked FAIL may handle I/O |
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at the same time. |
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Requests are distributed between paths to equalize load. |
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Requests are distributed between paths to equalize load. |
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For capable devices it allows to utilize bandwidth of all paths. |
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For capable devices it allows to utilize the bandwidth of all paths. |
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In Active/Read mode all paths not marked FAIL may handle reads same time, |
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In Active/Read mode all paths not marked FAIL may handle reads at the |
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but unlike Active/Active only one path handles write requests at any |
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same time, but unlike in Active/Active mode only one path handles write |
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point in time. |
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requests at any point in time. |
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It allows to closer follow original write request order if above layer |
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It allows to closer follow the original write request order if the layer |
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needs it for data consistency (not waiting for requisite write completion |
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above needs it for data consistency (not waiting for requisite write completion |
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before sending dependent write). |
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before sending dependent write). |
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.Pp |
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.Pp |
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When new devices are added to the system the |
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When new devices are added to the system the |
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Lines 269-277
GEOM class is given an opportunity to taste these new devices.
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If a new |
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If a new |
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device has a |
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device has a |
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.Nm MULTIPATH |
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.Nm MULTIPATH |
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on-disk metadata label, the device is used to either create a new |
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on-disk metadata label, the device is either used to create a new |
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.Nm MULTIPATH |
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.Nm MULTIPATH |
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GEOM, or been added the list of paths for an existing |
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GEOM, or added to the list of paths for an existing |
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.Nm MULTIPATH |
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.Nm MULTIPATH |
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GEOM. |
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GEOM. |
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.Pp |
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.Pp |
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Lines 281-287
and
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.Xr mpt 4 |
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.Xr mpt 4 |
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based Fibre Channel disk devices. |
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based Fibre Channel disk devices. |
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For these devices, when a device disappears |
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For these devices, when a device disappears |
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(due e.g., to a cable pull or power failure to a switch), the device is |
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(due to e.g. a cable pull or power failure to a switch), the device is |
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proactively marked as gone and I/O to it failed. |
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proactively marked as gone and I/O to it failed. |
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This causes the |
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This causes the |
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.Nm MULTIPATH |
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.Nm MULTIPATH |
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