drive usage with DDS enabled

Question

hello,

i have a customer with little problem with DDS. they have library with 2 LTO drives and about 4-5 storage nodes using that library. by default one SN used both drives in parallel. so other SN-s usually had to wait until one backup was finished.

i found parameter "max active devices" from SN properties. as i understood this instructs SN to use only one drive at the time. that was what customer wanted to do. but now they have strange behaviour. SN mounts only one tape and starts backup. when this tape gets full SN mounts new tape into second drive and continues with that. it does not unmount first tape from first drive. it only uses one tape at the time but 2 tapes are mounted until backup job finishes. then both drives are released. all other SN-s must wait until that.

is such behaviour normal? customer wants that one SN can only use one drive at the time to allow some other SN to use second drive.

regards,

kipz

benzino1 · Answer

Hi,Have a look into 'idle device timeout' and 'eject/unload/load sleep' parameters of jukebox resource.idle device timeout is:The number of minutes before an idle device is unmounted.This attribute only applies to SmartMedia, Silo, and shared nativejukeboxes with device sharing enabled. A value of zero disables this feature, volumes will not be unmounted from idle devices.

ble1 · Answer

Did you set this parameter to 1 for both devices on that storage node? Btw, if you wish to use one, why simply not share 2 devices not among all storage nodes but few of them... thus by calculating time window and drives associated you could come up with setup they would not wait for each other. But if you have backup window in which all storage nodes need to make a backup that I assume the only solution would be to increase number of drives or add disk for bck window backup and later during the day stage that at peace.

kipz1 · Answer

yes, we set idle device timeout parameter to 1 at both library and device level. unfortunately did not help.

problem is that there are some jobs taking long time and some jobs taking less time. so customer wanted to set that one job (storage node) can use only one drive at the time. so other storage nodes could use other drive. but unfortunately if during longtime job tape gets full this job mounts another tape to second drive and keeps both drives mounted but it only uses one. full tape does not get unmounted. and other jobs have to wait.

ble1 · Answer

Don't use that parameter then as without full tape will get unmounted.

NetWorker

drive usage with DDS enabled

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