On Aug 21, 2012, at 12:38 PM, Alan Brown <a...@mssl.ucl.ac.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/ ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
