Re: 24 gig Tape Settings
... Filemarks seperate files on tape, and because amanda stores each disk in the disklist in a seperate file on tape, it must account for any loss of capacity due to filemarks when estimating. ... Right. IIRC though this value is not currently used by or necessary for amanda so it's perfectly safe to set it to zero ... Amanda most definitely uses the value when calculating what will fit on a tape. The value zero can literally mean tape marks take up no space (actually, less than a KByte). Some tape technologies record file mark information in special tracks separate from the data, so they don't take up any (data) space, hence the appearance that they are zero length. Brandon D. Valentine John R. Jackson, Technical Software Specialist, [EMAIL PROTECTED]
Re: 24 gig Tape Settings
On Sat, 18 May 2002, Alexander Belik wrote: filemark 0 kbytes What is this? AIUI this is an approximation of the amount of space a filemark occupies on tape. Filemarks seperate files on tape, and because amanda stores each disk in the disklist in a seperate file on tape, it must account for any loss of capacity due to filemarks when estimating. IIRC though this value is not currently used by or necessary for amanda so it's perfectly safe to set it to zero which is what most of the tapetype entries you will find in the FAQ-O-Matic and here on the list have set it to. -- Brandon D. Valentine [EMAIL PROTECTED] Computer Geek, Center for Structural Biology This isn't rocket science -- but it _is_ computer science. - Terry Lambert on [EMAIL PROTECTED]
Re: 24 gig Tape Settings
On Sat, May 18, 2002 at 08:34:41AM +0300, Alexander Belik wrote:
On 17 May 2002, Jason L Tibbitts III wrote:
BH == Brook Hurd [EMAIL PROTECTED] writes:
BH I am about to use the following tape type: HP C5708A DDS-3 Data
BH Cartridge, 24GB
I've used:
define tapetype DDS-3 {
comment DDS-3 DAT drive
length 12288 mbytes # 12 GB
filemark 0 kbytes
speed 850 kbytes
}
filemark 0 kbytes What is this?
You didn't like the explanation I sent to you?
Tapetype measures the native capacity and will probably tell you something
like 11.6 GB with a filemark of 0, maybe 16KB. You ask later what the
latter is, it is wasted space (wasted to us) between files on the tape.
Each disklist entry is put on tape as one file. Some tape drives have
large filemarks. So a lot of disklist entries can eat lots of tape.
Not so with most modern drives.
--
Jon H. LaBadie [EMAIL PROTECTED]
JG Computing
4455 Province Line Road(609) 252-0159
Princeton, NJ 08540-4322 (609) 683-7220 (fax)
24 gig Tape Settings
I am about to use the following tape type: HP C5708A DDS-3 Data Cartridge, 24GB Unfortunatly, I don't see it listed online. Anybody use this type before, and if so, what are the correct settings? Thanks again for all your help, Brook
Re: 24 gig Tape Settings
BH == Brook Hurd [EMAIL PROTECTED] writes:
BH I am about to use the following tape type: HP C5708A DDS-3 Data
BH Cartridge, 24GB
I've used:
define tapetype DDS-3 {
comment DDS-3 DAT drive
length 12288 mbytes # 12 GB
filemark 0 kbytes
speed 850 kbytes
}
- J
Re: 24 gig Tape Settings
On Fri, 2002-05-17 at 15:08, Brook Hurd wrote: I am about to use the following tape type: HP C5708A DDS-3 Data Cartridge, 24GB I have used an HP C1537A DDS3 on Solaris7,8 and Linux with no problems. But not your specific model. Good Luck
Re: 24 gig Tape Settings
On Fri, 17 May 2002, Brook Hurd wrote:
I am about to use the following tape type:
HP C5708A DDS-3 Data Cartridge, 24GB
Unfortunatly, I don't see it listed online. Anybody use this type
before, and if so, what are the correct settings?
This is a 12GB native capacity DDS3 cartridge. Are these new tapes or
have they been used before? You will have to decide whether you want to
use hardware or software compression. With software compression you
tell amanda the exact native capacity of the tape. If you use hardware
compression you will have to guess about how well your data compresses
and lie to amanda about your tape capacity. I prefer to use software
compression and I would recommend that unless you're an amanda expert
you stick with software compression if you can. If these tapes have
ever been used before in a DAT drive with compression enabled you may
have trouble getting them to work with hardware compression disabled.
There was a thread here recently about degaussing DAT tapes to erase the
compression bit. You might look for it in the archives. If you don't
use hardware compression there are a number of DDS-3 tapetypes in the
FAQ-O-Matic which will work, depending on what model of DDS drive you
are using. Here's one for a Seagate drive for example:
define tapetype SEAGATE-DDS3 {
comment Seagate STD224000N-SB Internal DDS-3 Drive
length 11550 mbytes
filemark 0 kbytes
speed 1075 kps
}
Good luck.
--
Brandon D. Valentine [EMAIL PROTECTED]
Computer Geek, Center for Structural Biology
This isn't rocket science -- but it _is_ computer science.
- Terry Lambert on [EMAIL PROTECTED]
Re: 24 gig Tape Settings
On Fri, May 17, 2002 at 04:08:39PM -0400, Brook Hurd wrote:
HP C5708A DDS-3 Data Cartridge, 24GB
Unfortunatly, I don't see it listed online. Anybody use this type
before, and if so, what are the correct settings?
I use a HP DDS-3 too and I came across this definition somewhere which I use
define tapetype HP-DDS3 {
comment Seagate STD224000N-SB Internal DDS-3 Drive
length 11550 mbytes
filemark 0 kbytes
speed 1075 kps
}
You must bear in mind that a DDS-3 tape holds 12GB and NOT 24 GB of data,
despite what the marketing scum might like you to think. They assume a
compression ratio of 2:1 which I've never heard of ANYONE achieving (apart
from tape drive manufacturers in their contrived tests).
From an informal survey on the Sun Managers mailing list, it seemed that the
compression ratios people achieve in real life vary between 1.2:1 and 1.6:1.
If you're saving already compressed data e.g. JPEG files, you'll get no
compression at all. If you intend to use amanda to compress, use the figures
above and make sure your drive doesn't try to compress (some variation on
the mt command - depends on your local system). If you're not going to
compress with amanda, you could up the length figure here. But by what ?
As you've been using an 8 GB drive (which I presume was a DDS-2 hence was
really a 4GB drive) you should have some good data to go on - what was the
most data Amanda ever put on a tape ? If it was for instance 5GB then you'd
be reasonably safe using length 15000 mbytes.
I hope I've shed some light on what can be a confusing subject.
Kindest regards,
Niall O Broin
Re: 24 gig Tape Settings
On Fri, May 17, 2002 at 10:28:06PM +0100, Niall O Broin wrote: You must bear in mind that a DDS-3 tape holds 12GB and NOT 24 GB of data, despite what the marketing scum might like you to think. They assume a compression ratio of 2:1 which I've never heard of ANYONE achieving (apart from tape drive manufacturers in their contrived tests). I don't know, varies greatly with the data. Here are the results of the last full dumps of my disklist entries: butch /w/jg1 0.20 butch /opt 0.35 butch /w/tape8 0.35 winnie / 0.37 butch / 0.40 butch /usr 0.41 butch /w/dutch 0.45 butch /w 0.53 butch /win/c 0.55 butch /export0.62 butch /u 0.69 butch /var 0.70 winnie /cygdrive/c0.72 butch /images0.73 butch /u20.79 winnie /cygdrive/e0.91 winnie /cygdrive/d0.93 winnie /cygdrive/f0.96 butch /w/InstPkg 0.97 butch /w/Packages0.97 butch /d23.20 butch /d43.20 Anything under 0.5 is a 2:1 compression ration. One gave nearly 5:1. And of course several file systems were virtually uncompressible. It demonstrates the difficulty of guessing the hardware compressed capacity of a tape. BTW the last two entries are anomalies of totally empty file systems. -- Jon H. LaBadie [EMAIL PROTECTED] JG Computing 4455 Province Line Road(609) 252-0159 Princeton, NJ 08540-4322 (609) 683-7220 (fax)
Re: 24 gig Tape Settings
On 17 May 2002, Jason L Tibbitts III wrote:
BH == Brook Hurd [EMAIL PROTECTED] writes:
BH I am about to use the following tape type: HP C5708A DDS-3 Data
BH Cartridge, 24GB
I've used:
define tapetype DDS-3 {
comment DDS-3 DAT drive
length 12288 mbytes # 12 GB
filemark 0 kbytes
speed 850 kbytes
}
filemark 0 kbytes What is this?
--
[EMAIL PROTECTED]ICQ: 41776461
2:465/207@Fidonet Alexander Belik
http://www.vnet.dn.ua[EMAIL PROTECTED]
