Disks can be Hard Disk Drives(HDDs), Solid State Drives(SSDs), USB drives, virtual disks from a hypervisor or open LUKS mounts, or even sdcards. Rockstor supports and recommends whole disk btrfs (ie no partitions or partition table), but can also recognise and configure btrfs pool members in partitions; but this is not encourages. The recommendation to use whole disk btrfs pool members arises from the simplification afforded by removing the partition ‘layer’ all together. This way partition types, partition table types, sizes relative to whole disk, various limitations that exist on how many partitions of what type etc are all made irrelevant as each disk is simply and wholly a pool member and only a pool member. I.e. Keep it Simple and Straightforward (KISS).
Disk related operations such as S.M.A.R.T monitoring, data importing etc. can be managed from the Disks page listed under the Storage tab of the Web-UI. This page is an overview of disks currently or previously known to the system and is essentially a table where each row is an entry for a single real or virtual drive. Previously attached drives that are no longer found to be attached are re-named to detached-<random-string>. Attached devices are named according to their boot to boot stable udev assigned by-id names (ie /dev/disk/by-id entries). All devices require and are tracked by their unique serial number which allows for consistent settings even when a disk is moved from one pool to another (via sequential pool resize operations).
The Disks Web-UI page:
The disks table can be sorted by individual columns by clicking the small up/down arrows displayed in each column header. With a large numbers of disks the table will be paginated and the current page number is displayed below the table along with Prev and Next buttons.
Table links from left to right:-
Drive ‘by-id’ Name - see drive’s S.M.A.R.T / status.
Bulb Icon - flash drive’s activity light to identify it’s physical location.
Pool Name - Pools specific details page.
Pause Drive - request an immediate drive spin down (standby mode).
S.M.A.R.T Switch - enable or disable for each device.
For more information on configuring drive power down related settings please see the Disk Power Down HowTo. Similarly please see the Disk Custom S.M.A.R.T Options section of the S.M.A.R.T HowTo for details of the functions provided by the S.M.A.R.T column entries.
Rescan - the hardware for any supported drives, see Scan for Disk Changes below.
S.M.A.R.T - system wide custom configuration (advanced).
Scan for Disk Changes¶
Clicking the Rescan button forces an update of the Disk table. This is particularly useful if a drive has been added or removed since Rockstor was powered on ie hot plugged/unplugged. It is recommended that this action be taken just prior to removing detached devices to ensure the table contents is freshly updated.
Import BTRFS Pool¶
After having performed a Scan for Disk Changes any non Rockstor managed pools should be importable from any one of their Disk members, although if the chosen device member is a partition rather than a whole disk (as opposed to a whole disk partition) an additional step is required: that of Adding a Redirect Role.
The BTRFS Pool import procedure imports the following:-
Import whole disk BTRFS¶
If after a Scan for Disk Changes or after Reinstalling Rockstor the system finds an existing whole disk BTRFS filesystem a small down arrow icon next to pool member drive names will be visible. This down arrow can be used to import the btrfs filesystem, assuming all prior pool members are attached.
The import icon:
import icon tooltip “Click to import data (pools, shares and snapshots) on this disk automatically. Multi-device support included.”
or configure / wipe
configure or wipe icon tooltip “Disk is unusable because it has an existing whole disk BTRFS filesystem on it. Click to configure or wipe.”.
In this case we use the former import icon option and there after the disk table is as follows:
In the above the btrfs filesystem created (outside of Rockstor) was labeled “test-pool”.
Note: Rockstor requires btrfs labels and will name imported pools by the label found during the import process.
Import BTRFS in partition¶
Rockstor can also import btrfs pools that have partitioned members (although whole disk is recommended as this is a simpler arrangement). If at least one pool member is a whole disk btrfs (no partition table or partitions) then the above Import whole disk BTRFS method can be used on this whole disk member. But if all pool members are partitions then a manually applied ‘redirect role’ will be needed on one of the pool members in order to enable the import icon on that member. During the import all other partitioned members of the pool will have their required redirect roles applied automatically.
The following shows the tooltip guide for an as yet un-imported pre exiting single device btrfs in partition:
configure or wipe tooltip “Disk is unusable as it contains partitions: one of which has an existing BTRFS filesystem on it. A User Assigned redirect role is required prior to import. Click to configure or wipe.”
Disk Role Configuration¶
Disk roles are not required and are not advised for general purpose disk use. They are intended as a way to label individual disks for a specific use. Examples of such uses are documented on the configuration page:
N.B. Currently the only implemented role is The Disk Redirect Role
The Disk Redirect Role¶
Quoting from the configuration page:
“The Redirect role is always required for partitioned drives. Rockstor will only add the redirect role itself when importing a multi device pool with ‘btrfs in partition’ members. All other cases require user selection of the desired partition, including on the initial import device. Only one Redirect role (partition) per device is supported.
A drive’s Redirect role defines the Wipe action. A Redirect + Wipe erases a partitions data and filesystem. No Redirect + Wipe erases the entire drive and all it’s partitions. The wipe command used is “wipefs -a devname”. “
The Redirect role is essentially a pointer to the partition one wants to use on a disk instead of using the whole disk (recommended). No Redirect role (default) means “use whole disk”. The Select Partition to use option indicates the current setting by adding an active to that entry.
Examples of “Select Partition to use” entries and their explanation:
Whole Disk (None) - active means no redirect role and (None) means no whole disk filesystem found.
part2 (btrfs) - active an active redirect role to partition number 2 (btrfs filesystem).
Note that there is only ever one active entry at any one time.
Please note that there are some restrictions / safeguards in place that relate to devices containing a btrfs formatted partition. In this circumstance it is only possible to redirect to the btrfs partition; all other partition redirect requests will be blocked with the following warning message in red:
“Existing btrfs partition found; if you wish to use the redirect role either select this btrfs partition and import/use it, or wipe it (or the whole disk) and then re-assign. Redirection is only supported to a non btrfs partition when no btrfs partition exists on the same device.”
Also note that once a redirect role to a btrfs partition has been established it is by design that it cannot be changed to another partition until the btrfs filesystem in that partition is wiped; either via a resize - remove disk operation if it is a member of a pool, or by simply wiping it in the Disk Role Configuration page if it is not associated with any Rockstor managed pools. In this case the warning message in red is:
“Active btrfs partition redirect found; if you wish to change this redirect role first wipe the partition and then re-assign. Redirection is only supported to a non btrfs partition when no btrfs partition exists on the same device.”
See also related wipe restrictions towards the end of the Wiping a Partition or Whole Disk section.
Adding a Redirect Role¶
Rockstor has an ability to work with existing partitioned devices, however the recommendation is to use whole disks. But where this is specifically not desired or is otherwise unavoidable then a simple mechanism is available to allow the use of a single partition per disk (system disk not included). This covers most use cases and is a design decision intended to keep configuration simple.
If a disk has a partition table, it is suspected to have data and Rockstor doesn’t allow it’s use until a single partition is chosen (via a Redirect Role); or the partition table is explicitly wiped (removing all partitions and their contained data from the entire disk) and the disk is then usable in the preferred “Whole Disk” no redirect role mode.
Prior to configuration, partitioned disks are displayed with a little gear icon next to their name:
configure or wipe tooltip “Disk is unusable as it contains partitions and no User Assigned Role. Click to configure or wipe.”
N.B. a variation of this ‘cog icon’ tooltip message is observed if any of the exiting partitions are found to be un-imported btrfs members. See the above Import BTRFS in partition section for more details and an image showing this variation.
In either case clicking on this icon opens the Disk Role Configuration screen:
In the following we return to the Import BTRFS in partition example:
In this image we see the selection having been made but not yet submitted.
And once selected we Submit this Redirect role.
The resulting disk page entry then gains the import icon as Rockstor now has confirmation to use this particular partition and as seen in the previous image, it contained a btrfs filesystem.
import icon tooltip when importing from a partitioned pool member we have: “Click to import data (pools, shares and snapshots) on this partition automatically (Note: whole disk btrfs is recommended).”
Note the Role tags icon indicating this drive has a Role configured. If this was not a partitioned device the icon would be a single tag indicating a whole disk role (whole disk roles are a pending feature). Also note the difference / similarity of these two as yet un-imported pools, the first “Whole Disk” import option and the second “btrfs in partition” via a redirect role import option.
Clicking on either the tags icon (Redirect Role active) or the wipe / erase icon will display the Disk Role Configuration page where the current “active” setting for this partition redirect are displayed.
Note that the options now available mirror those of an existing as yet un-imported whole disk btrfs member: as seen in the Import whole disk BTRFS section: ie either import from, or wipe, the active selection.
If a redirect role is configured to a non btrfs partition then no import or wipe icons are displayed. And once imported the same is true for a btrfs partition:
In the above the btrfs filesystem created (outside of Rockstor) was purposefully labeled “btrfs-in-partition” to aid in this example.
Note: Rockstor requires btrfs labels and will name imported pools by the label found during the import process.
Wiping a Partition or Whole Disk¶
If not importing data from a pre-existing filesystem on a whole disk or in a partition it is recommended that each device first be wiped. This will remove all data and filesystem indicators on the wiped device; or in the case of a whole disk wipe, all partitions and the partition table as well.
N.B. When reusing a partition it is the users responsibility to ensure that the partition type is correct for the intended use. For ‘btrfs in partition’ this would be type ext2 (83 Linux). When using the default and recommended “Whole Disk” this caveat or complication is irrelevant as there will be no partitions or partition table (N.B. not to be confused with a partition that occupies the whole disk).
All partition or whole disk wiping is accomplished from the Disk Role Configuration screen and only an active selection can be wiped. If a partition or whole disk entry is not active, first select it and Submit this selection, this will change the “active” selection. Note that changing the “active” selection of a device can cause data loss so please consider this action carefully and read the configuration page warnings before proceeding. In the case of btrfs in partition some safeguards are in place and appropriate warning messages will indicate their presence: consequently there are restrictions on what can be done and in what order, especially in the case of an existing btrfs partition.
One such restriction is that only non Rockstor managed btrfs pool members can be wiped. If any device forms part of a Rockstor managed btrfs pool, attempts to wipe the device will be rejected with the following message in red:
“Selected device is part of a Rockstor managed pool. Use Pool resize to remove it from the relevant pool which in turn will wipe it’s filesystem.”
So it is first necessary to either remove the device from it’s pool or delete the entire pool before it’s members can be wiped. This is to avoid accidentally deleting a pool member.
Note the accompanying RED WARNING that appears once the erase icon tick is selected.
Rockstor detects when a device goes offline (dead or detached from the system) and marks it as such by changing it’s name to:
Also drive entries in this state gain a bin/trash icon next to their ‘detached’ name. This icon has the following tooltip text:
detached bin/trash icon tooltip “Disk is unusable because it is detached. Click to delete it from the system if it is not to be reattached.”
Clicking on the trash icon brings up a confirmation dialog. Upon confirmation, the disk will be removed:
It is important to note that this operation should only be carried out if the drive in question is not to be re-attached. Also not that this is not a ‘remove from pool’ operation but simply a ‘remove from database’ as there is not currently any btrfs pool functionality to this action so take care not to remove a detached drive that is part of a multi-device pool. It may be that the pool is not mounted as a result of this missing drive and simply re-attaching it (with the system off) is the way to go (ie failed connection).