Re: Backup to local tape; block size and performance??

Is there any way of calculating and/or playing about with the blocking
factor to optimize this backup? Or am I simply expecting too much of a
DLT tape drive and a 25GB backup ?
Not really , a DLT with 6MB native should backup the 25 GB in less
then 2 hours.


ANy thoughts/suggestions appreciated.....
Fronm this news group written in 2001
....
After reading some of the other responses, there seems to be some
confusion
about the tape block size versus the data buffer size (specified by
the backup
program). Setting the tape block size often doesn't have much affect,
but the
data buffer size can make a big difference. The simplest is to set the
tape
block size to 0 (variable), which in effect means to use a block size
equal to
the data buffer size, then use a larger buffer size with the backup
program, not
to exceed the physical buffer size of the tape drive. 64K is a good
default that
works on most drives, but higher-speed tape drives usually perform
better if you
up it to 256 or 512K.

Even the backup program documentaion can be confusing. If they have a
flag used
to indicate a block size, they're talking about the data buffer size,
not the
tape block size.

- Zitierten Text ausblenden -
- Zitierten Text anzeigen -
Nico Lammers wrote:
We have problems with our 7205 DLT tape drive (DLT4000 ).

This drive is very sensitive to block size. For example, using a block size
of 1024 and backing up 15GB of data will take approximately 6 hours. 15GB of
data backed up at a block size of 120.000 will take approximately three
hours. Small block sizes have a significant impact on performance, but only
a minimal impact on capacity. However, 2.6 format (density) and 6 format
(density) are significantly impacted in capacity by using small block sizes
because they do not pack the data in the internal block. Users should ensure
the block size they select is supported by their application. Compression
will depend upon the type of data. A compression ratio of 2:1 is assumed for
this compressed capacity.

Our problem is, that it is not fast enough. Can anybody help me with the
best configuration for this DLT 4000 for AIX 4.2 ?

nico.lamm...@xxxxxxxxx

----------------------------------------------
Anthony Johnson 1-619-291-4500
Storix Software 1-619-291-4590 (fax)
anth...@xxxxxxxxxx http://www.storix.com

Antworten Antwort an Autor Weiterleiten





Al Weston
Profil anzeigen
Weitere Optionen 18 Jan. 2001, 08:18
Newsgroups: comp.unix.aix
Von: Al Weston <alwes...@xxxxxxxxxxx>
Datum: 18 Jan 2001 01:17:17 -0600
Lokal: Do 18 Jan. 2001 08:17
Betreff: Re: How to configure DLT tape drive for AIX
Antwort an Autor | Weiterleiten | Drucken | Einzelne Nachricht |
Original anzeigen | Diese Nachricht melden | Nachrichten dieses Autors
suchen
I've spent a lot of time tweaking DLTs and found that variable block
size with a 64k data buffer workd best I routinely get over 30 gb an
hour with this configuration.

.....

.

Relevant Pages

  • RE: SBS 2003 SP2 / DLT compression?
    ... The NTbackup supports hardware compression, and it is based on the backup ... The two most common tape drives are DDS3, ... Hardware compression is turned on by default if you use SBS Backup ...
    (microsoft.public.windows.server.sbs)
  • Re: Export Entire SBS 2003 Registry
    ... The last USB backup was from 6pm on Friday and completed ... I gave up on tape drives a few years ago. ... server a few times to make sure it rebooted properly with all services ... ditch the tape drive and buy a set of USB drives to alternate for ...
    (microsoft.public.windows.server.sbs)
  • Re: Export Entire SBS 2003 Registry
    ... I gave up on tape drives a few years ago. ... Once you know you have a good backup to USB, ... server a few times to make sure it rebooted properly with all services ... ditch the tape drive and buy a set of USB drives to alternate for ...
    (microsoft.public.windows.server.sbs)
  • Re: Export Entire SBS 2003 Registry
    ... The last USB backup was from 6pm on Friday and completed ... I gave up on tape drives a few years ago. ... server a few times to make sure it rebooted properly with all services ... ditch the tape drive and buy a set of USB drives to alternate for ...
    (microsoft.public.windows.server.sbs)
  • Re: SBS Backup and RSM
    ... change creates uncertanties the day you have to do a full restore. ... I would use the NT backup information store backup, ... I greatly exceed the min requirements for SBS with both these ... tape drives all over the place and I don't have this problem with any ...
    (microsoft.public.windows.server.sbs)
Loading