Hi, sorry that it took some time...
On 6/2/2006 5:05 PM, Baptiste Malguy wrote: > Hello, > > I wish I could get more precise details for my case. Let's consider > backup are only made on some disks. > > In bacula-dir.conf, in Job resources, we may set Spool Data attribute to > yes. From the online doc, you can read: "This option should not be used > if you are writing to a disk file". > > I definitly understand this advice. Why spool on disk, while the final > storage is on a disk. > > However, I still want to run multiple Jobs in parallel AND avoid > interleaved backup data. As long as you've got enough disk space, you can and should use spooling. In my opinion, of course. > Furthermore, when I had to restore some small (< 100kb) files from a > disk volume > 50GB, I had to wait for more than 20 minutes. I don't > understand why it was so long. > > Here are my questions: > > 1 - Is it just the OS that takes so long to set its index to the content > of the disk volume (file) or is it Bacula that treats a disk volume as a > cartridge, with sequential access instead of random access ? That's a problem in Bacula which exists for a while. For reasons unknown to me, Kern foundd that file positioning doesn't work reliably for Bacula, so he disabled that code. Thus, as far as I know, Bacula treats file volumes even worse than tape ones - when searching, it reads each byte while tapes can usually be positioned faster than being read. > 2 - Based on the fact Bacula does not use random access to disk volumes, > what's the best deal between spooling data to avoid interleaved backups > data and havin interleaved backups data on disk volumes ? Use spooling, and limit the size of your volume files to something reasonable. Depending on how fast and often you have to run restores I'd recommend something between few GB to something like 50 GB. (Keep in mind that, depending on your filesystem, it can be necessary or helpful to create the file system Bacula uses with an inode density that closely fits to what Bacula will need.) > 3 - By the way, what do you think of havin a single ~ 60GB disk volume > or several smaller 5-10GB volumes ? Does anyone has some background > about it ? Yup, see above - several smaller ones are usually more efficient. > I'm not sure I've made myself clear. Do not hesitate to ask me to > reformulate. Not necessary, I think I understood your points ;-) Arno > > Arno Lehmann wrote: > >>Hi, >> >>On 6/2/2006 9:00 AM, Christoph Litauer wrote: >> >>>Dear bacula users, >>> >>>I currently backup about 15 linux/windows servers to a LTO streamer. For >>>increased restore speed I want no parallel (interleaving) backups on the >>>tapes. So I set "Maximum Concurrent Jobs" of the tape storage to 1. >>> >>>On the other hand, collecting data should happen in parallel on all >>>clients. So I set "SpoolData = yes" and "Maximum Concurrent Jobs" in the >>>sections "Director", "FileDaemon" (in clients bacula-fd.conf) and >>>"Storage" (bacula-sd.conf) to 20. >>> >>>I expected the clients to spool in parallel but despooling sequential. >>>But the clients wait for each other doing the backups on after another. >>>Did I miss something? >> >>Not exactly, but there's another solution to your needs. >> >>Activate spooling and allow multiple concurrent jobs. In this case, the >>data for one job will be written to tape consecutively (at least the >>amount that is spooled). Despooling happens per job, so during >>despooling there's only data from one job at a time going to tape. > > > >>If your spool space is smaller than what you'd need for all jobs you >>might end up with multiple chunks of data for a job, but these can be >>restored rather fast because Bacula can forward the tape between these >>chunks. >> >>This is the sort of setup I prefer because it gives me the right >>compromise between overall backup speed and restore speed. >> >>Arno >> >> > > > -- IT-Service Lehmann [EMAIL PROTECTED] Arno Lehmann http://www.its-lehmann.de _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
