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134 lines
4.6 KiB
C
134 lines
4.6 KiB
C
/*
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* Copyright (C) 2013 Andrea Mazzoleni
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __RAID_H
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#define __RAID_H
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/**
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* RAID mode supporting up to 6 parities.
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*
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* It requires SSSE3 to get good performance with triple or more
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* parities.
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*
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* This is the default mode used by SnapRAID.
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*/
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#define RAID_MODE_CAUCHY 0
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/**
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* RAID mode supporting up to 3 parities,
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*
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* It has a fast triple parity implementation even without SSSE3, but it
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* cannot go beyond it.
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* This is mostly intended for low end CPUs like ARM and AMD Athlon.
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*/
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#define RAID_MODE_VANDERMONDE 1
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/**
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* Max level of parity supported in the default mode RAID_MODE_CAUCHY.
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*/
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#define RAID_PARITY_MAX 6
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/**
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* Maximum number of data disks.
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* Limit of the parity generator matrix used.
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*/
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#define RAID_DATA_MAX 251
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/**
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* Initializes the RAID system.
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*/
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void raid_init(void);
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/**
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* Sets the mode to use. One of RAID_MODE_*.
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*
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* You can change mode at any time, and it will affect next calls to raid_par(),
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* raid_rec() and raid_recpar().
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*
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* The two modes are compatible for the first two levels of parity.
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* The third one is different.
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*/
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void raid_mode(int mode);
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/**
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* Sets the zero buffer to use in recovering.
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*
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* Before calling raid_rec() and raid_recpar() you must provide a memory
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* buffer filled with zero with the same size of the blocks to recover.
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*/
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void raid_zero(void* zero);
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/**
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* Computes the parity.
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*
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* \param np Number of parities to compute.
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* \param nd Number of data disks.
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* \param size Size of the blocks pointed by vv. It must be a multipler of 64.
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* \param vv Vector of pointers to the blocks for disks and parities.
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* It has (::nd + ::np) elements.
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* Each element points to a buffer of ::size bytes.
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*/
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void raid_par(int np, int nd, size_t size, void** vv);
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/**
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* Recovers failures of data disks using the specified parities.
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*
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* Only the data blocks are recovered. The parity buffers are destroyed.
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* If you want also to recompute parities, you can use raid_recpar().
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*
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* \param nr Number of failed data disks to recover.
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* \param id[] Vector of ::nr indexes of the data disks to recover.
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* The indexes start from 0. They must be in order.
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* \param ip[] Vector of ::nr indexes of the parity disks to use for recovering.
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* The indexes start from 0. They must be in order.
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* \param nd Number of data disks.
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* \param size Size of the blocks pointed by vv. It must be a multipler of 64.
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* \param vv Vector of pointers to the blocks for disks and parities.
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* It has (::nd + ::ip[::nr - 1] + 1) elements. The first elements are the blocks
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* for data, following with the parity blocks. Each blocks has ::size bytes.
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*/
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void raid_rec(int nr, const int* id, const int* ip, int nd, size_t size, void** vv);
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/**
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* Recovers failures of data and parity disks.
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*
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* It's similar at raid_rec() but it also recovers parities.
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*
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* In case there are more parities available than needed, ones to use are
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* automatically selected, excluding the ones specified in the ::ip vector.
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*
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* Ensure to have ::nrd + ::nrp <= ::np, otherwise recovering is not possible.
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*
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* \param nrd Number of failed data disks to recover.
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* \param id[] Vector of ::nrd indexes of the data disks to recover.
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* The indexes start from 0. They must be in order.
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* \param nrp Number of failed parity disks to recover.
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* \param ip[] Vector of ::nrp indexes of the parity disks to recover.
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* The indexes start from 0. They must be in order.
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* Note that as difference than raid_rec() these are the failed parities.
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* All the parities not specified here are assumed correct, and they are
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* not recomputed.
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* \param np Number of parity disks.
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* \param nd Number of data disks.
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* \param size Size of the blocks pointed by vv. It must be a multipler of 64.
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* \param vv Vector of pointers to the blocks for disks and parities.
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* It has (::nd + ::np) elements. The first elements are the blocks
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* for data, following with the parity blocks. Each blocks has ::size bytes.
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*/
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void raid_recpar(int nrd, const int* id, int nrp, int* ip, int np, int nd, size_t size, void** vv);
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#endif
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