It has got nothing to see with disk pools but with collocation. When you
set collocation on for the tape storage pool, it automatically tries to put
the data of each client on a different tape. So if 5 clients backup at the
same time on th disk pool, they will automatically be migrated to 5 tapes
instead of one. So the backup will need more tape mounts but the restore
less tape mounts.
But I must admit I didn't understand fully your question, what do you mean
by other disk pools messing up ?
Etienne GUILLAUMONT
e-mail : etienne AT rgb-technologie DOT fr
RGB Technologie
Parc d'Innovation, Bâtiment PYTHAGORE
11 Rue Jean SAPIDUS
67400 ILLKIRCH
Tél : 03 90 40 60 60
Fax : 03 90 40 60 61
William Rosette
<Bill_Rosette@PAPA To: ADSM-L AT VM.MARIST DOT
EDU
JOHNS.COM> cc:
Sent by: "ADSM: Subject: Re: progressive
backup vs. full + incremental
Dist Stor Manager"
<[email protected].
EDU>
06/03/2003 18:11
Please respond to
"ADSM: Dist Stor
Manager"
How do you get a disk pool to go to a certain amount of tapes without the
other disk pools messing them up?
Thank You,
Bill Rosette
Data Center/IS/Papa Johns International
WWJD
GUILLAUMONT
Etienne To:
ADSM-L AT VM.MARIST DOT EDU
<eguillau@RGB-TECH cc:
NOLOGIE.FR> Subject: Re: progressive
backup vs. full + incremental
Sent by: "ADSM:
Dist Stor Manager"
<[email protected].
EDU>
03/06/2003 12:00
PM
Please respond to
"ADSM: Dist Stor
Manager"
It depends on the size of your disk pool and on the size of the backup you
have to do each day. Just to be more precise, imagine you have 50 clients
with an average on 10 Gb on each client and a LTO library. If you set
collocate to yes, each client will backup on the disk pool and TSM will put
the data of each client on a separate tape, you just need to have enough
disk to accumulate the files while TSM changes the tapes, it's not
mandatory but it will allow you not having clients waiting a tape mount
before ending their schedule. When it reaches the last tape, it will put
the others clients on the used tapes. For example client1 on tape1 client2
on tape2 ... client20 on tape20 and then client21 on tape1 client22 on
tape2 ... and so on. but if you don't set collocation, each day, all the
clients will backup on one tape and then, each client will need 20 mounts
to restore instead of one or two. That's what I did on my site, I have some
clients with little to backup, one or two GB and they are put on the same
tapes than others. The only thing is that you have no empty tape in you
storage pool but a lot of filling tapes.
But TSM is clear about that : you must choose between rapid backup and
rapid restore so between nocollocation and collocation.
I agree that if you have a full backup with all the data of the client
contiguous on the tape, it will be faster to restore. But most of time,
several clients backups at the same time and so the data is not contiguous,
even with a full backup.
I didn't wrote that one drive would be faster but easier for disaster
recovery. I said easier because you don't have to worry : everithing is on
the same tape. I even made once a system backup followed by the data backup
on AIX. Even if the computer burnt, you just needed a single tape an no
software to restore completely the server, booting on the tape. Could you
imagine more easy ? I wish each OS had the same functionalities. And I must
admit I was thinking of smaller servers which can be backed up completely
on one single tape, not of servers with one terabyte for which I agree with
you : you must have a backup software if you want to backup these servers
or wait LTO 5 in some years :-)
Regards
Etienne GUILLAUMONT
e-mail : etienne AT rgb-technologie DOT fr
RGB Technologie
Parc d'Innovation, Bâtiment PYTHAGORE
11 Rue Jean SAPIDUS
67400 ILLKIRCH
Tél : 03 90 40 60 60
Fax : 03 90 40 60 61
William Rosette
<Bill_Rosette@PAPA To: ADSM-L AT VM.MARIST DOT
EDU
JOHNS.COM> cc:
Sent by: "ADSM: Subject: Re: progressive
backup vs. full + incremental
Dist Stor Manager"
<[email protected].
EDU>
06/03/2003 17:14
Please respond to
"ADSM: Dist Stor
Manager"
A collocate with 50 clients to 20 tapes sounds like nocollocate. How do
you do this and keep separate schedules for each client?
On the Incremental/full, if full is done weekly then the maximum possible
tapes for restore will be 5 tapes (4 M-Th nights, +1 for full) versus the
possible maximum of 20 tapes is 20 tapes above.
On the Differential/full, with full done weekly then the maximum possible
tapes for restore is 2 tapes (last Differential + 1 for full) versus 5 and
20 above. Add minimum 3 minutes per tape (1 minute to load tape, 1 minute
to dismount, & 1 minute to locate) and I see a 2 tape restore take 30
minutes, 5 tape restore take 39 minutes and the 20 tape restore take 1 hour
24 minutes. This also depends on how the restore go's. That 3 minute per
tape could be more if a tape is used more than once which I have seen
happen depending which file is being restored.
On the last item I disagree with the fastest way is 1 drive per computer.
That means you can only restore the speed of the tape drive which might not
be good if you have 1 TB of disk to restore. I think the TSM way is the
best by splitting your resources. We have 10 tape drives that average 50
GB an hour per drive. If the Server and Client could handle it (which
seems to be my most bottlenecks) I could go 500 GB per hour and that 1 TB
would restore in 2 hours.
What I can't get over is how at TSM classes they try to beat it into my
head that Restores are #1 priority, why can't that be with TSM software?
Thank You,
Bill Rosette
Data Center/IS/Papa Johns International
WWJD
GUILLAUMONT
Etienne To:
ADSM-L AT VM.MARIST DOT EDU
<eguillau@RGB-TECH cc:
NOLOGIE.FR> Subject: Re: progressive
backup vs. full + incremental
Sent by: "ADSM:
Dist Stor Manager"
<[email protected].
EDU>
03/06/2003 04:24
AM
Please respond to
"ADSM: Dist Stor
Manager"
I don't understand why collocation should use more tapes. Of course it
would be probably better to have one tape by client but if you manage to
backup for example 50 small clients on 20 tapes, you could use collocation
without buying more tapes. The difference would be that instead of backing
up each day all the clients on the last tape, resulting in each client
having files on each tape, it will put 2 or 3 clients on each tape. In
fact, at the end, you will probabbly have something like each client having
files on 2 or three tapes.
With full+incremental, depending on the regularity of your full backups,
you could have a client on far more tapes, tipically 1 full per week + 4
incremental.
With full+differential, you would have each client on 2 tapes, but the
amount of data backed up would be bigger because a file modified just after
the last full backup would be on each subsequent differential tape.
And in fact, as long as I know, most software based on full+incremental are
unable of collocation and use more tapes than TSM.
But in all cases, the most easy way to restore a full disk or a full
computer is to attach a single drive to this computer and make a full
backup of this computer each day. Most of my clients make that and in case
of a disk failure, everything is simple : you mount the last backup and
restore it completely. But if you need a single file .... and if you have
20 computers to backup ....
Etienne GUILLAUMONT
e-mail : etienne AT rgb-technologie DOT fr
RGB Technologie
Parc d'Innovation, Bâtiment PYTHAGORE
11 Rue Jean SAPIDUS
67400 ILLKIRCH
Tél : 03 90 40 60 60
Fax : 03 90 40 60 61
William Rosette
<Bill_Rosette@PAPA To: ADSM-L AT VM.MARIST DOT
EDU
JOHNS.COM> cc:
Sent by: "ADSM: Subject: Re: progressive
backup vs. full + incremental
Dist Stor Manager"
<[email protected].
EDU>
05/03/2003 16:21
Please respond to
"ADSM: Dist Stor
Manager"
This progressive incremental confuses me. This is what I thought was going
on:
1. Differential is all changes from last FULL backup.
2. Incremental is all changes from last ANY backup
3. Full is all files not matter change on backup.
We used to do Differential with Weekend Fulls. During a restore we would
restore Full if file had not changed, and then the last differential for
the other files that changed. We never restored more than necessary. It
depended on the restore. Restore 1 file was the same on Differential as
Incremental (most current or before corruption). The problem comes when
you are restoring directories or a whole system as in DR. In the
Differential Weekend Full world you would restore Full and lay on top the
last Differential and your done. Always 2 restores was all and restores
flew since data was all together.
Now the TSM world has its own database with its own reclamation,
expiration, migration, collocation, and the works. Come restoring 1 file it
is the same as above. Come restoring directories or whole systems it will
depend where all the data is. Our case, if the restore is not far back we
have a quick restore, but the further back we go in date the slower the
restore because of the no-collocation and the data is spread over 100's of
tapes. This seems to be the same as an Incremental that the TSM database
keeps track of every file from every tape.
Thus, the reason we did not use Incrementals before was 1. Restores were
long, 2. No database to keep track of all Incremental tapes, 3.
Differential & Full used less tapes, and 4. money. I am still dealing with
the progressive incremental that progressively eats resources/money. My
suggestion would be for reclamations to reclaim to a collocate status or
somehow keeping the data together as it gets older. Right now I am
probably going to run FULLs just to keep my restores to a minimum since the
tape issue will hurt us if we collocate
If I am off, I would appreciate anyone that can straighten out my
backups/restores.
Thank You,
Bill Rosette
Data Center/IS/Papa Johns International
WWJD
Gianluca Mariani1
<gianluca_mariani@ To:
ADSM-L AT VM.MARIST DOT EDU
IT.IBM.COM> cc:
Sent by: "ADSM: Subject: Re: progressive
backup vs. full + incremental
Dist Stor Manager"
<[email protected].
EDU>
03/05/2003 09:47
AM
Please respond to
"ADSM: Dist Stor
Manager"
Progressive incremental backs up only new or changed files. during the
initial backup the client backs up all eligible files of course(full
backup). Subsequently, files are backed up again only if they are new or
have changed since the last backup. In TSMs case, a pointer to each version
of every file for every client is kept in the database , so there is no
need for another full backup.
When you need to restore, you can choose the specific version of the file
or point-in-time to restore, and TSM will restore only that particular
file or files. The approach used for full + incremental backups (NetBackup)
requires an initial full backup, followed by regular incremental or
differential backups (usually once a day), with the complete cycle needing
a full backup to be repeated on a regular (usually weekly) basis. This
backup method results in redundant weekly full backups of files that have
not changed, wasting both network and media resources. The multi-step
restore process in this approach requires the software to restore the last
full backup, then to restore incremental or differential backups on top
of that in order to recover the latest version of a file or an entire
system. This methodology not only involves restoring more data, it also
means more tape mounts and tape positioning and consumes more network
bandwidth all of which amounts to having longer restore times.
Cordiali saluti
Gianluca Mariani
Tivoli TSM Global Response Team, Roma
Via Sciangai 53, Roma
phones : +39(0)659664598
+393351270554 (mobile)
gianluca_mariani AT it.ibm DOT com
----------------------------------------------------------------------------------------------------
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Joni Moyer
<joni.moyer@HIG
HMARK.COM> To
Sent by: "ADSM: ADSM-L AT VM.MARIST DOT EDU
Dist Stor cc
Manager"
<ADSM-L AT VM DOT MARI
bcc
ST.EDU>
Subject
progressive backup vs. full +
05/03/2003 incremental
15.21
Please respond
to "ADSM: Dist
Stor Manager"
Hello everyone!
I was wondering why the full + incremental would result in a longer restore
time than the progressive backup methodology? From several co-workers
point of view they thought that it would be quicker on the full +
incremental because you wouldn't have to go back to the beginning backups
of the file and restore all of the incrementals, you would just go back to
the most recent full backup and apply the incrementals after that point.
When I went to explain the reasoning behind this, I had some problems
understanding the concept myself, so I was hoping someone could explain
both methods and why they differ in restore time and why progressive is
better than the full + incremental. Thank you so much for any help you can
lend on this matter!
Joni Moyer
Systems Programmer
joni.moyer AT highmark DOT com
(717)975-8338
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