System and method for eliminating performance impact of information collection from media drives
Embodiments described herein can avoid such speed degradations caused by performance monitoring. According to one embodiment, a media drive monitoring device can issue a command that does not penetrate reservations at the drive. If the drive is reserved, the drive will return a reservation conflict (“RC”) or other status indicating the previous reservation. The monitoring device can continue to issue the command to the drive until the drive responds in a manner that indicates that it is no longer reserved. The monitoring appliance can then issue a command to collect information from the drive (e.g., the Log Sense command or other command).
1. A media library monitoring system comprising:
a media library monitoring device including a processor and non-transitory computer memory having instructions translatable by the processor, the media library monitoring device coupled to multiple drives in a media library via a switch on a network comprising a storage area network, wherein the media library is coupled to one or more hosts via the switch and the media library monitoring device is an out-of-band device connected to the switch and external to the media library, the media library monitoring device configured to:
determine whether a reservation is established at a drive of the media library;
based on a determination that the reservation is established at the drive, repeatedly send a reservation testing command to the drive of the media library through the switch, wherein the reservation testing command is selected to not penetrate the reservation at the drive and to elicit a status from the drive indicating whether the reservation is established at the drive;
receive data generated in response to the reservation testing command from the media library and forwarded by the switch; and
responsive to receiving an indication in the data the reservation is not established at the drive, send one or more commands to the drive to collect performance information from the drive, wherein the out-of-band device collects the performance information from the drive without intercepting commands to the drive from one or more hosts connected to the drive via the switch or without intercepting responses from the drive to the one or more hosts.
2. The media library monitoring system of claim 1 , wherein the media library monitoring device communicates Small Computer System Interface commands to the one or more drives.
3. The media library monitoring system of claim 2 , wherein the reservation testing command is a Test Unit Ready Command.
4. The media library monitoring system of claim 3 , wherein the one or more commands configured to collect performance information comprise a Log Sense Command.
5. The media library monitoring system of claim 1 , wherein the media library monitoring device is configured to repeatedly send the reservation testing command according to a schedule.
6. The media library monitoring system of claim 1 , wherein the media library monitoring device is configured to test, based on a setting indicating a set of drives in the media library, whether reservations are established at the set of drives in the media library.
7. A media library monitoring device comprising:
a controller to connect to a transport medium;
a processor coupled to the controller;
a computer readable medium accessible by the processor and storing a set of computer instructions executable to cause the media library monitoring device to:
communicate with multiple drives of a media library physically separate from the media library monitoring device via a switch over a network comprising a storage area network, wherein the media library monitoring device is an out-of-band device connected to the switch;
determine whether a reservation is established at a drive of the media library;
based on a determination that the reservation is established at the drive, repeatedly send a reservation testing command over the transport medium to the drive of the media library through the switch, wherein the reservation testing command sent to the drive is selected to not penetrate the reservation at the drive and to elicit a status from the drive indicating whether the reservation is established at the drive;
receive data generated in response to the reservation testing command from the media library and forwarded by the switch; and
in response to receiving an indication in the data that the reservation is not established at the drive, send one or more commands to the drive to collect performance information from the drive, wherein the out-of-band device collects the performance information from the drive without intercepting commands to the drive from one or more hosts connected to the drive via the switch or without intercepting responses from the drive to the one or more hosts.
8. The media library monitoring device of claim 7 , wherein the reservation testing command and the one or more commands to collect performance information are Small Computer System Interface commands.
9. The media library monitoring device of claim 8 , wherein the reservation testing command is a Test Unit Ready Command.
10. The media library monitoring device of claim 9 , wherein the one or more commands configured to collect performance information comprise a Log Sense Command.
11. The media library monitoring device of claim 7 , wherein the media library monitoring device is configured to repeatedly send the reservation testing command according to a schedule.
12. The media library monitoring device of claim 7 , wherein the media library monitoring device is configurable to test, based on a setting indicating a set of drives in the media library, whether reservations are established at the set of drives in the media library.
13. A method of monitoring a media library comprising:
connecting a media library monitoring device to multiple drives in the media library via a switch on a network comprising a storage area network, wherein the media library monitoring device is an out-of-band device connected to the switch and external to a media library having one or more drives, the media library coupled to one or more hosts via the switch;
determining whether a reservation is established at a drive of the media library;
based on a determination that the reservation is established at the drive, repeatedly sending, by the media library monitoring device, a reservation testing command over the network to the drive of the media library through the switch, wherein the reservation testing command sent to the drive does not penetrate the reservation at the drive and elicits a status from the drive indicating whether the reservation is established at the drive;
receiving data generated in response to the reservation testing command from the media library and forwarded to the media library monitoring device by the switch; and
responsive to receiving an indication in the data that the reservation is not established at the drive, sending by the media library monitoring device, one or more commands over the network to the drive to collect performance information from the drive, wherein the out-of-band device collects the performance information from the drive without intercepting commands from the one or more hosts to the drive or without intercepting responses from the drive to the one or more hosts when the data from the drive indicates that the reservation is not established.
14. The method of claim 13 , wherein the reservation testing command and the one or more commands to collect performance information are SCSI commands.
15. The method of claim 14 , wherein the reservation testing command is a Test Unit Ready Command.
16. The method of claim 15 , wherein the one or more commands configured to collect performance information comprise a Log Sense Command.
17. The method of claim 13 , wherein the reservation testing command is sent according to a schedule.
18. The method of claim 14 , further comprising testing, based on a setting indicating a set of drives in the media library, whether reservations are established at the set of drives in the media library.