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A single tool to manage your storage.
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System Storage Manager ********************** A single tool to manage your storage. Description *********** System Storage Manager provides easy to use command line interface to manage your storage using various technologies like lvm, btrfs, encrypted volumes and more. In more sophisticated enterprise storage environments, management with Device Mapper (dm), Logical Volume Manager (LVM), or Multiple Devices (md) is becoming increasingly more difficult. With file systems added to the mix, the number of tools needed to configure and manage storage has grown so large that it is simply not user friendly. With so many options for a system administrator to consider, the opportunity for errors and problems is large. The btrfs administration tools have shown us that storage management can be simplified, and we are working to bring that ease of use to Linux filesystems in general. Licence ******* (C)2011 Red Hat, Inc., Lukas Czerner <lczerner@redhat.com> This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. Commands ******** Introduction ************ System Storage Manager have several commands you can specify on the command line as a first argument to the ssm. They all have specific use and its own arguments, but global ssm arguments are propagated to all commands. Create command ************** This command creates a new volume with defined parameters. If **device** is provided it will be used to create a volume, hence it will be added into the **pool** prior the volume creation (See *Add command section*). More devices can be used to create a volume. If the **device** is already used in the different pool, then **ssm** will ask you whether you want to remove it from the original pool. If you decline, or the removal fails, then the **volume** creation fails if the *SIZE* was not provided. On the other hand, if the *SIZE* is provided and some devices can not be added to the **pool** the volume creation might succeed if there is enough space in the **pool**. *POOL* name can be specified as well. If the pool exists new volume will be created from that pool (optionally adding **device** into the pool). However if the *POOL* does not exist **ssm** will attempt to create a new pool with provided **device** and then create a new volume from this pool. If **--backend** argument is omitted, the default **ssm** backend will be used. Default backend is *lvm*. **ssm** also supports creating RAID configuration, however some back- ends might not support all the levels, or it might not support RAID at all. In this case, volume creation will fail. If **mount** point is provided **ssm** will attempt to mount the volume after it is created. However it will fail if mountable file system is not present on the volume. List command ************ List informations about all detected devices, pools, volumes and snapshots found in the system. **list** command can be used either alone to list all the information, or you can request specific section only. Following sections can be specified: {volumes | vol} List information about all **volumes** found in the system. {devices | dev} List information about all **devices** found in the system. Some devices are intentionally hidden, like for example cdrom, or DM/MD devices since those are actually listed as volumes. {pools | pool} List information about all **pools** found in the system. {filesystems | fs} List information about all volumes containing **filesystems** found in the system. {snapshots | snap} List information about all **snapshots** found in the system. Note that some back-ends does not support snapshotting and some can not distinguish between snapshot and regular volume. in this case **ssm** will try to recognize volume name in order to identify **snapshot**, but if the **ssm** regular expression does not match the snapshot pattern, this snapshot will not be recognized. Remove command ************** This command removes **item** from the system. Multiple items can be specified. If the **item** can not be removed for some reason, it will be skipped. **item** can represent: device Remove **device** from the pool. Note that this can not be done in some cases where the device is used by pool. You can use **-f** argument to *force* removal. If the device does not belong to any pool, it will be skipped. pool Remove the **pool** from the system. This will also remove all volumes created from that pool. volume Remove the **volume** from the system. Note that this will fail if the **volume** is mounted and it can not be *forced* with **-f**. Resize command ************** Change size of the **volume** and file system. If there is no file system only the **volume** itself will be resized. You can specify **device** to add into the **volume** pool prior the resize. Note that **device** will only be added into the pool if the **volume** size is going to grow. If the **device** is already used in the different pool, then **ssm** will ask you whether you want to remove it from the original pool. In some cases file system has to be mounted in order to resize. This will be handled by **ssm** automatically by mounting the **volume** temporarily. Check command ************* Check the file system consistency on the **volume**. You can specify multiple volumes to check. If there is no file system on the **volume**, this **volume** will be skipped. In some cases file system has to be mounted in order to check the file system This will be handled by **ssm** automatically by mounting the **volume** temporarily. Snapshot command **************** Take a snapshot of existing **volume**. This operation will fail if back-end which the **volume** belongs to does not support snapshotting. Note that you can not specify both *NAME* and *DESC* since those options are mutually exclusive. In some cases file system has to be mounted in order to take a snapshot of the **volume**. This will be handled by **ssm** automatically by mounting the **volume** temporarily. Add command *********** This command adds **device** into the pool. The **device** will not be added if it's already part of different pool by default, but user will be asked whether to remove the device from it's pool. When multiple devices are provided, all of them are added into the pool. If one of the devices can not be added into the pool for any reason, add command will fail. If no pool is specified, default pool will be chosen. In the case of non existing pool, it will be created using provided devices. Backends ******** Introduction ************ Ssm aims to create unified user interface for various technologies like Device Mapper (dm), Btrfs file system, Multiple Devices (md) and possibly more. In order to do so we have a core abstraction layer in "ssmlib/main.py". This abstraction layer should ideally know nothing about the underlying technology, but rather comply with **device**, **pool** and **volume** abstraction. Various backends can be registered in "ssmlib/main.py" in order to handle specific storage technology implementing methods like *create*, *snapshot*, or *remove* volumes and pools. The core will then call these methods to manage the storage without needing to know what lies underneath it. There are already several backends registered in ssm. Btrfs backend ************* Btrfs is the file system with many advanced features including volume management. This is the reason why btrfs is handled differently than other *conventional* file systems in **ssm**. It is used as a volume management back-end. Pools, volumes and snapshots can be created with btrfs backend and here is what it means from the btrfs point of view: pool Pool is actually a btrfs file system itself, because it can be extended by adding more devices, or shrink by removing devices from it. Subvolumes and snapshots can also be created. When the new btrfs pool should be created **ssm** simply creates a btrfs file system, which means that every new btrfs pool has one volume of the same name as the pool itself which can not be removed without removing the entire pool. Default btrfs pool name is **btrfs_pool**. When creating new btrfs pool, the name of the pool is used as the file system label. If there is already existing btrfs file system in the system without a label, btrfs pool name will be generated for internal use in the following format "btrfs_{device base name}". Btrfs pool is created when **create** or **add** command is used with devices specified and non existing pool name. volume Volume in btrfs back-end is actually just btrfs subvolume with the exception of the first volume created on btrfs pool creation, which is the file system itself. Subvolumes can only be created on btrfs file system when the it is mounted, but user does not have to worry about that, since **ssm** will automatically mount the file system temporarily in order to create a new subvolume. Volume name is used as subvolume path in the btrfs file system and every object in this path must exists in order to create a volume. Volume name for internal tracking and for representing to the user is generated in the format "{pool_name}:{volume name}", but volumes can be also referenced with its mount point. Btrfs volumes are only shown in the *list* output, when the file system is mounted, with the exception of the main btrfs volume - the file system itself. New btrfs volume can be created with **create** command. snapshot Btrfs file system support subvolume snapshotting, so you can take a snapshot of any btrfs volume in the system with **ssm**. However btrfs does not distinguish between subvolumes and snapshots, because snapshot actually is just a subvolume with some block shared with different subvolume. It means, that **ssm** is not able to recognize btrfs snapshot directly, but instead it is trying to recognize special name format of the btrfs volume. However, if the *NAME* is specified when creating snapshot which does not match the special pattern, snapshot will not be recognized by the **ssm** and it will be listed as regular btrfs volume. New btrfs snapshot can be created with **snapshot** command. device Btrfs does not require any special device to be created on. Lvm backend *********** Pools, volumes and snapshots can be created with lvm, which pretty much match the lvm abstraction. pool Lvm pool is just *volume group* in lvm language. It means that it is grouping devices and new logical volumes can be created out of the lvm pool. Default lvm pool name is **lvm_pool**. Lvm pool is created when **create** or **add** command is used with devices specified and non existing pool name. volume Lvm volume is just *logical volume* in lvm language. Lvm volume can be created wit **create** command. snapshot Lvm volumes can be snapshotted as well. When a snapshot is created from the lvm volume, new *snapshot* volume is created, which can be handled as any other lvm volume. Unlike *btrfs* lvm is able to distinguish snapshot from regular volume, so there is no need for a snapshot name to match special pattern. device Lvm requires *physical device* to be created on the device, but with **ssm** this is transparent for the user. Crypt backend ************* Crypt backend in **ssm** is currently limited to only gather the information about encrypted volumes in the system. You can not create or manage encrypted volumes or pools, but it will be extended in the future. Environment variables ********************* SSM_DEFAULT_BACKEND Specify which backend will be used by default. This can be overridden by specifying **-b** or **--backend** argument. Currently only *lvm* and *btrfs* is supported. SSM_LVM_DEFAULT_POOL Name of the default lvm pool to be used if **-p** or **--pool** argument is omitted. SSM_BTRFS_DEFAULT_POOL Name of the default btrfs pool to be used if **-p** or **--pool** argument is omitted. SSM_PREFIX_FILTER When this is set **ssm** will filter out all devices, volumes and pools which name does not start with this prefix. It is used mainly in **ssm** test suite to make sure that we do not scramble local system configuration. Quick examples ************** List system storage: # ssm list ---------------------------------- Device Total Mount point ---------------------------------- /dev/loop0 5.00 GB /dev/loop1 5.00 GB /dev/loop2 5.00 GB /dev/loop3 5.00 GB /dev/loop4 5.00 GB /dev/sda 149.05 GB PARTITIONED /dev/sda1 19.53 GB / /dev/sda2 78.12 GB /dev/sda3 1.95 GB SWAP /dev/sda4 1.00 KB /dev/sda5 49.44 GB /mnt/test ---------------------------------- ------------------------------------------------------------------------------ Volume Pool Volume size FS FS size Free Type Mount point ------------------------------------------------------------------------------ /dev/dm-0 dm-crypt 78.12 GB ext4 78.12 GB 45.01 GB crypt /home /dev/sda1 19.53 GB ext4 19.53 GB 12.67 GB part / /dev/sda5 49.44 GB ext4 49.44 GB 29.77 GB part /mnt/test ------------------------------------------------------------------------------ Creating a volume of defined size with the defined file system. The default back-end is set to lvm and lvm default pool name is lvm_pool: # ssm create --fs ext4 -s 15G /dev/loop0 /dev/loop1 The name of the new volume is '/dev/lvm_pool/lvol001'. Resize the volume to 10GB: # ssm resize -s-5G /dev/lvm_pool/lvol001 Resize the volume to 100G, but it would require to add more devices into the pool: # ssm resize -s 25G /dev/lvm_pool/lvol001 /dev/loop2 Now we can try to create new lvm volume named 'myvolume' from the remaining pool space with xfs file system and mount it to /mnt/test1: # ssm create --fs xfs --name myvolume /mnt/test1 List all volumes with file system: # ssm list filesystems ----------------------------------------------------------------------------------------------- Volume Pool Volume size FS FS size Free Type Mount point ----------------------------------------------------------------------------------------------- /dev/lvm_pool/lvol001 lvm_pool 25.00 GB ext4 25.00 GB 23.19 GB linear /dev/lvm_pool/myvolume lvm_pool 4.99 GB xfs 4.98 GB 4.98 GB linear /mnt/test1 /dev/dm-0 dm-crypt 78.12 GB ext4 78.12 GB 45.33 GB crypt /home /dev/sda1 19.53 GB ext4 19.53 GB 12.67 GB part / /dev/sda5 49.44 GB ext4 49.44 GB 29.77 GB part /mnt/test ----------------------------------------------------------------------------------------------- You can then easily remove the old volume by: # ssm remove /dev/lvm_pool/lvol001 Now lest try to create btrfs volume. Btrfs is separate backend, not just a file system. That is because btrfs itself have integrated volume manager. Defaul btrfs pool name is btrfs_pool.: # ssm -b btrfs create /dev/loop3 /dev/loop4 Now create we btrfs subvolumes. Note that btrfs file system has to be mounted in order to create subvolumes. However ssm will handle it for you.: # ssm create -p btrfs_pool # ssm create -n new_subvolume -p btrfs_pool # ssm list filesystems ----------------------------------------------------------------- Device Free Used Total Pool Mount point ----------------------------------------------------------------- /dev/loop0 0.00 KB 10.00 GB 10.00 GB lvm_pool /dev/loop1 0.00 KB 10.00 GB 10.00 GB lvm_pool /dev/loop2 0.00 KB 10.00 GB 10.00 GB lvm_pool /dev/loop3 8.05 GB 1.95 GB 10.00 GB btrfs_pool /dev/loop4 6.54 GB 1.93 GB 8.47 GB btrfs_pool /dev/sda 149.05 GB PARTITIONED /dev/sda1 19.53 GB / /dev/sda2 78.12 GB /dev/sda3 1.95 GB SWAP /dev/sda4 1.00 KB /dev/sda5 49.44 GB /mnt/test ----------------------------------------------------------------- ------------------------------------------------------- Pool Type Devices Free Used Total ------------------------------------------------------- lvm_pool lvm 3 0.00 KB 29.99 GB 29.99 GB btrfs_pool btrfs 2 3.84 MB 18.47 GB 18.47 GB ------------------------------------------------------- ----------------------------------------------------------------------------------------------- Volume Pool Volume size FS FS size Free Type Mount point ----------------------------------------------------------------------------------------------- /dev/lvm_pool/lvol001 lvm_pool 25.00 GB ext4 25.00 GB 23.19 GB linear /dev/lvm_pool/myvolume lvm_pool 4.99 GB xfs 4.98 GB 4.98 GB linear /mnt/test1 /dev/dm-0 dm-crypt 78.12 GB ext4 78.12 GB 45.33 GB crypt /home btrfs_pool btrfs_pool 18.47 GB btrfs 18.47 GB 18.47 GB btrfs /dev/sda1 19.53 GB ext4 19.53 GB 12.67 GB part / /dev/sda5 49.44 GB ext4 49.44 GB 29.77 GB part /mnt/test ----------------------------------------------------------------------------------------------- Now let's free up some of the loop devices so we cat try to add them into then btrfs_pool. So we'll simply remove lvm mvolume and resize lvol001 so we can remove /dev/loop2. Note that myvolume is mounted so we have to unmount it first.: # umount /mnt/test1 # ssm remove /dev/lvm_pool/myvolume # ssm resize -s-10G /dev/lvm_pool/lvol001 # ssm remove /dev/loop2 Add device to the btrfs file system: # ssm add /dev/loop2 -p btrfs_pool Set' see what happend. Note that to actually see btrfs subvolumes you have to mount the file system first: # mount -L btrfs_pool /mnt/test1/ # ssm list volumes ------------------------------------------------------------------------------------------------------------------------ Volume Pool Volume size FS FS size Free Type Mount point ------------------------------------------------------------------------------------------------------------------------ /dev/lvm_pool/lvol001 lvm_pool 15.00 GB ext4 15.00 GB 13.85 GB linear /dev/dm-0 dm-crypt 78.12 GB ext4 78.12 GB 45.33 GB crypt /home btrfs_pool btrfs_pool 28.47 GB btrfs 28.47 GB 28.47 GB btrfs /mnt/test1 btrfs_pool:2012-05-09-T113426 btrfs_pool 28.47 GB btrfs 28.47 GB 28.47 GB btrfs /mnt/test1/2012-05-09-T113426 btrfs_pool:new_subvolume btrfs_pool 28.47 GB btrfs 28.47 GB 28.47 GB btrfs /mnt/test1/new_subvolume /dev/sda1 19.53 GB ext4 19.53 GB 12.67 GB part / /dev/sda5 49.44 GB ext4 49.44 GB 29.77 GB part /mnt/test ------------------------------------------------------------------------------------------------------------------------ Remove the whole lvm pool and one of the btrfs subvolume, and one unused device from the btrfs pool btrfs_loop3. Note that with btrfs, pool have the same name as the volume: # ssm remove lvm_pool /dev/loop2 /mnt/test1/new_subvolume/ Snapshots can also be done with ssm: # ssm snapshot btrfs_pool # ssm snapshot -n btrfs_snapshot btrfs_pool With lvm, you can also create snapshots: root# ssm create -s 10G /dev/loop[01] # ssm snapshot /dev/lvm_pool/lvol001 Now list all snapshots. Note that btrfs snapshots are actually just subvolumes with some blocks shared with the original subvolume, so there currently no way to distinguish between those. ssm is using a little trick to search for name patters to recognize snapshots, so if you specify your own name for the snapshot ssm will not recognize it as snapshot, but rather as regular volume (subvolume). This problem does not exist with lvm.: # ssm list snapshots ------------------------------------------------------------------------------------------------------------- Snapshot Origin Volume size Size Type Mount point ------------------------------------------------------------------------------------------------------------- /dev/lvm_pool/snap20120509T121611 lvol001 2.00 GB 0.00 KB linear btrfs_pool:snap-2012-05-09-T121313 18.47 GB btrfs /mnt/test1/snap-2012-05-09-T121313 ------------------------------------------------------------------------------------------------------------- Installation ************ To install System Storage Manager into your system simply run: python setup.py install as root in the System Storage Manager directory. Make sure that your system configuration meet the *requirements* in order for ssm to work correctly. Note that you can run **ssm** even without installation from using the local sources with: bin/ssm.local Requirements ************ Python 2.6 or higher is required to run this tool. System Storage Manager can only be run as root since most of the commands requires root privileges. There are other requirements listed bellow, but note that you do not necessarily need all dependencies for all backends, however if some of the tools required by the backend is missing, the backend would not work. Python modules ============== * os * re * sys * stat * argparse * datetime * threading * subprocess System tools ============ * tune2fs * fsck.SUPPORTED_FS * resize2fs * xfs_db * xfs_check * xfs_growfs * mkfs.SUPPORTED_FS * which * mount * blkid * wipefs Lvm backend =========== * lvm2 binaries Btrfs backend ============= * btrfs progs Crypt backend ============= * dmsetup * cryptsetup For developers ************** We are accepting patches! If you're interested contributing to the System Storage Manager code, just checkout the git repository located on SourceForge. Please, base all of your work on the "devel" branch since it is more up-to-date and it will save us some work when merging your patches: git clone --branch devel git://git.code.sf.net/p/storagemanager/code storagemanager-code Any form of contribution - patches, documentation, reviews or rants are appreciated. See *Mailing list section* section. Tests ===== System Storage Manager contains regression testing suite to make sure that we do not break thing that should already work. And we recommend every developer to run tests before sending patches: python test.py Tests in System Storage Manager are divided into four levels. 1. First the doctest is executed. 2. Then we have unittests in "tests/unittests/test_ssm.py" which is testing the core of ssm "ssmlib/main.py". It is checking for basic things like required backend methods and variables, flag propagations, proper class initialization and finally whether commands actually result in the proper backend callbacks. It does not require root permissions and it does not touch your system configuration in any way. It actually should not invoke any shell command, and if it does it's a bug. 3. Second part of unittests is backend testing. We are mainly testing whether ssm commands result in proper backend operations. It does not require root permissions and it does not touch your system configuration in any way. It actually should not invoke any shell command and if it does it's a bug. 4. And finally there are real bash tests located in "tests/bashtests". Bash tests are divided into files. Each file tests one command for one backend and it containing series of test cases followed by checks whether the command created the expected result. In order to test real system commands we have to create system device to test on and not touch any of the existing system configuration. Before each test a number of devices are created using *dmsetup* in the test directory. These devices will be used in test cases instead of real devices. Real operation are performed in those devices as it would on the real system devices. It implies that this phase requires root privileges and it would not be run otherwise. In order to make sure that **ssm** does not touch any existing system configuration, each device, poor and volume name is include special prefix and SSM_PREFIX_FILTER environment variable is set to make **ssm** to exclude all items which does not match this filter. Even though we tried hard to make sure that the bash tests does not change any of your system configuration the recommendation is **not** to run tests as with root privileges on your work or production system, but rather run it on your testing machine. If you change or create new functionality, please make sure that it is covered by the System Storage Manager regression test suite to make sure that we do not break it unintentionally. Important: Please, make sure to run full tests before you send a patch to the mailing list. To do so, simply run "python test.py" as root on your test machine. Documentation ============= System Storage Manager documentation is stored in "doc/" directory. The documentation is build using **sphinx** software which help us not to duplicate texts for different type of documentation (man page, html pages, readme). If you are going to modify documentation, please make sure not to modify manual page, html pages or README directly, but rather modify "doc/*.rst" and "doc/src/*.rst" files accordingly so the change is propagated to all documents. Moreover, parts of the documentation such as *synopsis* or ssm command *options* are parsed directly from the ssm help output. It means that when you're going to add or change argument into **ssm** the only thing you have to do is to add or change it in the "ssmlib/main.py" source code and then run "make dist" in the "doc/" directory and all the documents should be updated automatically. Important: Please make sure you update the documentation when you add or change **ssm** functionality if the format of the change requires it. Then regenerate all the documents using "make dist" and include changes in the patch. Mailing list ============ System Storage Manager developers communicate via the mailing list. Address of our mailing list is storagemanager- devel@lists.sourceforge.net and you can subscribe on the SourceForge project page https://lists.sourceforge.net/lists/listinfo /storagemanager-devel. Mailing list archives can be found here http://sourceforge.net/mailarchive/forum.php?forum_name =storagemanager-devel. This is also the list where to send patches and where the review process is happening. We do not have separate *user* mailing list, so feel free to drop your questions there as well. Posting patches =============== As already mentioned, we are accepting patches! And we are very happy for every contribution. If you're going to send a path in, please make sure to follow some simple rules: 1. Before you're going to post a patch, please run our regression testing suite to make sure that your change does not break someone else work. See *Tests section* 2. If you're making a change that might require documentation update, please update the documentation as well. See *Documentation section* 3. Make sure your patch have all the requisites such as *short description* preferably 50 characters long at max describing the main idea of the change. *Long description* describing what was changed with and why and finally Signed-off-by tag. 4. If you're going to send a patch to the mailing list, please send the patch inlined in the email body. It is much better for review process. Hint: You can use **git** to do all the work for you. "git format-patch" and "git send-email" will help you with creating and sending the patch.
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