On Tue, Nov 23, 2010 at 12:35:10PM -0500, upengan78 wrote: > Firstly, thanks for the response! > > 1. You have 50 gig under backup/amanda control, but how much data > are you currently backing up per week ? > > Currently not doing any backups through Amanda. I am trying to understand > this whole theory of numbers involved in configuration. > I want to start backing up a 50G partition with a Full backup on Monday and > incrementals on each day till next week's Monday. So I think for 7 days I > will have to backup 50G + 200M x 6 days = 50.6G . Let's say 55G a week.
When you first run amanda it will see that you have no dumps of any of the DLEs (DiskList Entries) and will want to dump level 0 for all of them. Not knowing the physical config - local drives, networked amanda clients, bus architecture, you might consider starting with only a few DLE in your disklist file and adding a couple each day. Once you have a 'recent' dump, that is a level 0 without one dumpcycle, you will (tend to) perform non-0 dumps for other days. You talk in terms of 'new data' each day, do you touch existing files ? Its not a block level dump, its a file level dump so if you are appending to existing files or modifying existing files other than those you are creating with new data you will be backing them up also, so you may backup more data than you expect. How many DLEs, disklist entries, will you have, what are their relative sizes ? > My original configuration is with little idea. > dumpcycle 7 > runspercycle 7 > tapecycle 20 > I though above would yield me 7 Days of backup including 1 Full and 6 > incrementals in 1 dumpcycle and all 20 tapes will be used. I don't know if I > am right. Correct in principle, in practice its a little more complicated. Once amanda gets a handle on the DLE sizes it will try to level the amanda of data across each day of dumps in the dumpcycle. This will take a while and you will find that if you have 'lots' of free space in your tape pool amanda may promote level 0 dumps and perform them for any given DLE in less than dumpcycle days. > 2. With current settings, tapecycle and dumpcycle you will have > between 2 and 3 full dumps per partition "on tape" at any one > time, 2.x X 50 Gig >> 80 Gig so you are already short on (vtape) space. > > Correct I think I also think I am short of Vtapes. I wonder if I should add > more 4.xx G size tapes or redo Vtapes of 40G size each to utilize whole 300GB > of disk space. Did you plan on using the VTape pool for anything else ? How large are your DLEs ? Are they actually all small enough to expect level 0 dumps to fit on 4 gig volumes ? > 3. I believe that vtape size is an upper bound, unused space on > the vtape is actually free space on the disk, so you can actually > oversubscribe the 300 gig pool by some percentage (depending on > numerous factors that we currently do NOT have a handle on). > > I am not sure I understand what oversubscribe actually is but I wonder if I > really need it. could you tell me what it will actually do in my case? Oversubscribe the vtape pool drive... I think if you, for instance, use vtapes of 10 gig and on some day write 6 gig that you have 4 gig of real space free. I don't think the vtapes are fixed size containers. This would leave 4 gig free that day and ultimately enough free space to have, 300/10 = 30 vtapes, perhaps 35 vtapes in the tape pool. Actual numbers depend on how full each tape will be, compression ration if you use it, that sort of thing. > 4. With 4 Gig tapes... how large are your DLEs ? 4 Gig is relatively > small, are you using tape spanning or are all of the DLE's small ? > > I don't believe Tape spanning is configured. I just used Vtapes document from > Amanda wiki and so used 4GB dvd size as it is mentioned there. that's why I > am here now to tweak it. DLEs in my disklist are as below, > > amandaclient.domain.com /backup/location comp-tar Ah - how many DVD do you typically write per day now ? Is that all level 0 or a mix of 0 and non-0 dumps ? Are you manually intermixing the levels now to even out dump times across your week ? If so, you can achieve the same result with amanda, but the scheduling becomes automatic. You don't normally want to force the levels but let amanda choose them for you. > 5. With 4-gig tapes and 50 gig under backup you must use 12 tapes > for a complete dump of the system, with a pool of 20 tapes you > can not have two complete dump cycles... > > Okay. that makes sense. > 6. It seems that either I'm badly misunderstanding your config or > you are badly underconfiguring your tape pool. > > Yes, I can provide you whatever is required. I know even 300G may not very > large but then I'd like to have best possible that I can make use of it as of > now. Thanks for helping me out! 300 Gig is more than large enough to manage backups on 50 Gig of data. What is the structure of your vtape pool ? One large spindle ? Raid 5, raid 6 ? a pair of raid 1 drives (mirrored) ? Do you need to think in terms of off-site storage for disaster recovery ? Are you worried about data recovery if you lose the vtape pool as well as files/drives in your data pool ? > Thanks > > +---------------------------------------------------------------------- > |This was sent by [email protected] via Backup Central. > |Forward SPAM to [email protected]. > +---------------------------------------------------------------------- > > --- Brian R Cuttler [email protected] Computer Systems Support (v) 518 486-1697 Wadsworth Center (f) 518 473-6384 NYS Department of Health Help Desk 518 473-0773 IMPORTANT NOTICE: This e-mail and any attachments may contain confidential or sensitive information which is, or may be, legally privileged or otherwise protected by law from further disclosure. It is intended only for the addressee. If you received this in error or from someone who was not authorized to send it to you, please do not distribute, copy or use it or any attachments. Please notify the sender immediately by reply e-mail and delete this from your system. Thank you for your cooperation.
