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This section describes general considerations and known limitations,
including:
Do not enable diagnostics on
the console
During routine operation, do not issue the CLI command diag
enable from the console. Diagnostic output sent to the
console can sometimes interfere with operations such as disk shelf
firmware upgrades. If diagnostics are enabled, you can disable them
with the CLI command diag disable.
Repeatedly issuing the CLI command shelffirmware status from the
console can cause VTL crash
Repeatedly issuing the CLI command shelffirmware status
from the console might trigger an assertion and crash of the VTL.
If this happens, reboot the VTL. The problem does not cause any
form of data loss or corruption. The problem does not occur if you
are issuing CLI commands from, for example, an ssh session.
Kernel panic during shelf firmware upgrade when there is I/O activity
On a VTL system that is undergoing a shelf firmware upgrade, any
type of I/O
activity may cause a kernel panic. This applies to any type of I/O
activity
such as frontend reads and writes and backend exports and clones.
There should be absolutely no I/O activity while a VTL system
is undergoing a shelf firmware upgrade. Additionally, diagnostics
must be disabled on the VTL console with the command diag
disable, if the console is connected.
If this kernel panic does happen, reboot the VTL. This kernel panic
does not result in data loss or corruption.
Appliance stops instead of rebooting after firmware upgrade
After a firmware upgrade, you are prompted to reboot the VTL appliance.
Sometimes instead of rebooting after the firmware upgrade, the appliance
stops responding. If this happens, power cycle the appliance. After
the VTL is power-cycled, it boots with the new firmware version.
Cannot downgrade disk or shelf
firmware
Do not install an earlier release of disk or shelf firmware than
is already installed on the disk or shelf.
Operational restrictions
while upgrading firmware
Make sure there are no backup, restore, import, export, or clone
operations in progress during a disk or disk shelf firmware upgrade.
Do not reboot or power cycle a VTL, or disk shelves, during a disk
or disk shelf firmware upgrade.
Maximum number of slots per library
The recommended maximum number of slots per library is 1024.
This limit is not enforced, but it becomes difficult to use the
GUI for some tasks when this limit is exceeded. The maximum supported
number of slots per appliance is 10,000.
Some restrictions on drive/application/server
combinations
Some combinations of otherwise supported tape devices, backup applications
and backup servers are not currently supported. The not supported
combinations include the following:
-
STK10000 tape drives, NetBackup, and Windows platforms
-
DTL-S4 tape drives, NetBackup, and Suse Linux platforms
-
IBM 3592 tape drives, NetWorker, and Solaris platforms
-
IBM 3592 tape drives, TSM, and Windows platforms
-
IBM 3592 tape drives, NetVault, and Suse Linux platforms
The combination of
IBM 3592 tape drives, TSM, and AIX platforms is supported, but with
this combination TSM sometimes displays incorrect reports of IO
errors.
Check the NearStore
VTL Compatibility List for supported tape drives, applications
and backup servers.
VTL300/700/1400 appliance notes
and limitations
Note the following features and limitations of the VTL300/700/1400
appliances:
- All VTL300/700/1400 Fibre Channel ports support 4 Gbps, although
the disk shelves restrict back-end port performance to 2 Gbps.
- VTL300 appliances support a maximum of five shelves and two
front-end ports.
- VTL300 appliances require an optional HBA, if you want to connect
the appliance to a tape device. The optional HBA provides two
tape ports.
- For improved performance, VTL700/1400 appliances support an
optional, second hardware compression card (installed in slot
4).
- For VTL700 appliances, if you are attaching more than 12 shelves,
you must add to the basic configuration an additional HBA (installed
in slot 3) for disks.
- If you have a basic VTL700/1400 appliance, and need additional
back-end ports (for example to attach a tape device) you can do
these things:
- Configure port 0d as a back-end port using the GUI task
Configuration Tasks > Advanced > Options.
- Add an additional HBA to slot 3 and add four back-end ports.
- Add an additional HBA to slot 4 and add four back-end ports.
Note that PCI slot 4 can also be used for the optional additional
hardware compression card, so you can add one or the other,
but not both.
- Parallel SCSI is not supported on these platforms, although
you can connect parallel SCSI tape devices by using a SCSI-to-Fibre
Channel bridge.
VTL600/1200 appliance note
All of the virtual drive types supplied with VTL 5.2.3 allocate
disk space assuming disk compression is used. Libraries defined
before upgrading to VTL 5.2.3 are not affected by an upgrade to
VTL 5.2.3, but if you install VTL 5.2.3, have software disk compression
disabled, and you delete the entire VTL configuration, before building
a new configuration, you must adjust the virtual drive types to
allocate more disk space per virtual tape. For example, if your
tape device compression ratio is 2:1, update the Disk Allocation
Per Tape (GB) parameter on all virtual libraries to allocate twice
the disk space as the physical tape capacity.
Action- and event- reporting can
be excessive
Some error conditions, and some operating conditions, can generate
multiple, repetitive messages, resulting in an excessive number
of actions and events.
Removing all barcode ranges does
not clear inventory listing
If you remove all barcode ranges from an ACSLS library, the inventory
does not update.
After removing compression card, uncompressed
writes are slow
If all compression cards are removed from a VTL appliance that
previously had compression cards, uncompressed data writes might
be slow. Once an appliance has used a compression card, the card
is checked before all writes, so even uncompressed writes are delayed
while waiting for the compression card to respond. Replacing the
compression card restores normal performance.
Editing console input has some
limitations
Some line editing functions, such as using up and down arrow keys
to scroll through command line history, are not available when using
the command line interface from the console, although available
when using a session over ssh.
Admin cannot see customer-owned
virtual tapes
If the customer option is enabled, a customer is created, and the
customer creates some virtual libraries, an admin user will not
be able to see those virtual libraries in the Virtual Tape List
GUI screen.
Changes to licensing require a reboot
After adding or removing a license key, you need to reboot the
appliance before the license becomes effective.
Although compression is
enabled, imported virtual tapes do not use compression
When physical tapes are imported to a virtual library, the resulting
virtual tapes are not compressed, even if compression is set on
the virtual tape. If you overwrite the entire virtual tape, the
new data is compressed.
Hardware compression card
disappears
Occasionally after a reboot, one or more hardware compression cards
might not be detected. If this happens, the system automatically
attempts to clear the problem by rebooting once. If this does not
clear the problem, an Action Required notification is issued and
the system remains up.
SCSI Addresses screen data might be
formatted incorrectly
If both port mapping and host access are enabled, and multiple
ports are mapped to a device, the display on the SCSI Addresses
screen for the second port and LUN might be formatted incorrectly.
Rows after the first incorrectly formatted row might also be incorrectly
formatted.
Disks with older firmware might
become unresponsive after being plugged back in
Systems with 500 GB disks and versions of disk shelf firmware prior
to AT-FCX version 32 might become unresponsive after the disks are
unplugged and plugged back in. You might also observe many "I/O
not completing" messages on the console.
You can prevent this problem by upgrading the disk shelf firmware
on your NearStore VTL appliances. The NearStore VTL software version
5.2.3 package includes updated shelf firmware that you can install.
Unexpected I/O interruptions
occur when creating more virtual devices
I/O might get interrupted from the virtual drives during the addition
of a new virtual library or the expansion of an existing library.
This is because the VTL sends out UNIT ATTENTION on all the LUNs
to inform the initiator that the REPORT LUNS data has changed.
AutoSupport notification might
fail during NearStore VTL startup
While a NearStore VTL appliance is starting up, conditions might
occur that trigger an AutoSupport notification e-mail message, but
if the network is not yet initialized, the attempt will fail. In
such a case, the usual event action logging will occur on the appliance,
but NetApp technical support will not receive notification.
A NearStore VTL might attempt to use
a tape drive even after detecting a hardware failure in the drive
A NearStore VTL appliance might retry a failed physical tape drive,
rather than redirect I/O to another available physical tape drive.
If this occurs, disable the failed tape drive.
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