Topic: tape speed

[Karl Ponsonby]

Can somebody,anybody give me some idea as to the speed and av. throughput of tape backup.
I am backing up about 13gig of data and its taking about 5 hours to do this. It's on a Quantum DLT7000 with a Adaptec aci-7xxx built into the motherboard. It works fine and outputs the result to email, but I've never had much to do with tape backups. Any help or ideas....

Again,
Thanks all
Karl

[ralph]

Hi Karl,

you can assume getting a throughput of round about 10 MB/s on youre tapedrive.
This is the maximum rate for a DLT7k.
To get that rate, you have to "feed" the tapedrive with round about 15 - 18 MB/s over the SCSI Bus. Your adaptec controller should be capable of transferring 40 MB/s brutto ( nettorate ~ 27 ) which should be sufficient.

The critical factor in that chain may be your hdds. In case they are IDE hmmmm.

Anyhow, depending on software used and the other stuff mentioned above, one can get round about 36 GB/h out of the tapedrive ( or on to ).

cheers,

Ralph

[Boris]

That speed sounds to optimistic to me. In reality I’ve seen average speed from 1.5 MB/s for IDE drives, to 2-3MB/s for SCSI (single drive).
I am backing up 28Gb to VXA-1 tape on very fast server with hardware SCSI RAID and it takes 6+ hours.
Your speed may be different depends on the hardware, and likely can be tweaked to double (?) of your current, but anyway your are not far off from the average real live backup speed.

[Karl Ponsonby]

Thanks Boris and Ralph for your responses.

I changed the byte size from 10 to 32 in the template and the backup report now states Av throughput of 2069 KB/s. 13302.66 M/B took 1hour 50 minutes.
This is much better, but I suppose listining to you guys, then this is about as much as I can get.
System details.. 2x P3 650, 768M ram, 2x4.5g's SCSI 1x 18g SCSI on channel 'A' and  1x 18g SCSI on ch 'B' with tape drive. 4.5g's running SME o/s in software raid 1 and 18g's running /home software raid 1.
Agaim thanks for your help,
Karl

[Karl Ponsonby]

Whoops, forgot to mention that I also changed the compression ratio to ' 2 ', instead of ' 4 '.
Karl

[Karl Ponsonby]

Whoops, forgot to mention that I also changed the compression ratio to ' 2 ', instead of ' 4 '.
Karl

[Shad Lords]

I'm currently backing up off of a IDE drive to a SCSI AIT-1 drive and these are the following statistics that I am getting.

Backup OK, "90302" files, "12565" MB, "4686" seconds, "160" MB/mn

-Shad

[Boris]

That is about average to "faster then average" for this type of setup. 2-3 MB/sec is not bad.