Re: [Bacula-users] Bacula Linux and the LTO-4 tape speed
2012-08-21 12:41:47
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)
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.
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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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