Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed
2012-08-21 12:52:54
On Aug 21, 2012, at 12:38 PM, Alan Brown <ajb2 AT mssl.ucl.ac DOT uk> wrote:
> On 21/08/12 16:04, Dan Langille wrote:
>
>> ###
>> The DLT drive default data block transfer size is 4KB (4096 bytes).
>> To achieve better performance, adjust block size to 32K bytes or
>> higher when using a fixed block device.
>> ###
>
> What you want to know is how big it can go - and the only way to know that is
> to experiment.
>
> Assuming your DLTs are DLT8000, 12 hours is about spot-on for the raw
> capacity and speed of the tape (40GB raw + 7GB/hour)
In my case, DLT7000.
> I'm seeing unspool speeds of about 150MB/sec to LTO5 using 2MB block sizes
> (that's max, smaller block sizes get used too), and tests show the spool
> (raid0 4 * Intel 64GB SLCs) is capable of something like 800MB/s r/w with
> several streams running (1400MB/s single sustained read to /dev/null)
>
> That means there's some room for improvement in despooling speed, but the big
> bottleneck at the moment is disk-fd and fd->sd, not sd->tape - the best
> achieved there is a sustained 52MB/s and that virtually maxes out a 1Gb/s
> NIC. Even if the network block sizing is optimized, I need to look at 10Gb
> NICs and for simultaneous spool/despooling.
>
>
> WRT "offsite backups" - I'm more inclined to use a good firesafe in another
> building than pass media to a 3rd party company. Far too many people backup
> to tape but then don't take care of the media.
All my backups are in my basement. Including the tapes. I really should move
the latest full backups somewhere else.
--
Dan Langille
http://langille.org/
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- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, (continued)
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, Dan Langille
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, Alan Brown
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, lst_hoe02
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, Alan Brown
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, lst_hoe02
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed,
Dan Langille <=
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, Alan Brown
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, Phil Stracchino
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, lst_hoe02
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, lst_hoe02
- Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, Dan Langille
Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed, Alan Brown
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