On 05/19/2015 11:42 AM, Bryn Hughes wrote:
...
> recent LTO versions (5/6) you really need to make sure your disk setup 
> on your backup storage server is capable of keeping up with the tape 
> drive - most consumer hard drives top out at about 120MB/sec for 
> sequential reads and much less than that for random I/O (such as having 
> backup jobs writing to the disk at the same time as the tape drive is 
> reading from it)

Wow these seagate nas drives must be magic then: it's 120MB/s sequential
read yet I get consistent 340MB/s sustained writes

> 11-May 23:00 starfish-sd JobId 13: Despooling elapsed time = 00:02:24, 
> Transfer rate = 345.8 M Bytes/second
...
> 12-May 12:30 starfish-sd JobId 13: Despooling elapsed time = 00:02:25, 
> Transfer rate = 343.4 M Bytes/second
...
> 14-May 03:33 starfish-sd JobId 34: Despooling elapsed time = 00:02:27, 
> Transfer rate = 338.8 M Bytes/second
...
> 18-May 19:49 starfish-sd JobId 57: Despooling elapsed time = 00:02:26, 
> Transfer rate = 341.1 M Bytes/second

and so on. On software raid-5-ish (raidz1) with lz4 compression at
filesystem level.

How about you iostat that LTO 5/6 drive while a restore job is reading
from it and a backup job is writing at the same time and then post speed
comparisons?

-- 
Dimitri Maziuk
Programmer/sysadmin
BioMagResBank, UW-Madison -- http://www.bmrb.wisc.edu

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