After research, I started using 512k blocks, 3 years ago, for LTO5 tapes.
For LTO7 I might have to research even more, but certainly 512k or bigger.
Debra Baddorf
Fermilab
> On Jan 11, 2018, at 2:09 PM, Jean-Louis Martineau <jmartin...@carbonite.com>
> wrote:
>
> Luc,
>
> amtapetype use speed heuristic to detect if the drive is in compressed
> mode, it might not be good for newer drives.
>
> Why you didn't post the complete amtapetype output? I can't tell you why
> the heuristic is bad without those numbers.
>
> The default block size of 32k was good 15 years ago, but it is really
> bad for new drives. You should really think about increasing it a lot.
>
> Jean-Louis
>
> On 11/01/18 02:56 PM, Luc Lalonde wrote:
> > I sent the wrong output in the last email.... Here's the correct
> > 'tapeinfo':
> >
> > Product Type: Tape Drive
> > Vendor ID: 'IBM '
> > Product ID: 'ULTRIUM-HH7 '
> > Revision: 'G9Q1'
> > Attached Changer API: No
> > SerialNumber: '123456789A'
> > MinBlock: 1
> > MaxBlock: 8388608
> > SCSI ID: 4
> > SCSI LUN: 0
> > Ready: yes
> > BufferedMode: yes
> > Medium Type: 0x78
> > Density Code: 0x5c
> > BlockSize: 32768
> > DataCompEnabled: no
> > DataCompCapable: yes
> > DataDeCompEnabled: yes
> > CompType: 0xff
> > DeCompType: 0xff
> > BOP: yes
> > Block Position: 0
> > Partition 0 Remaining Kbytes: -1
> > Partition 0 Size in Kbytes: -1
> > ActivePartition: 0
> > EarlyWarningSize: 0
> > NumPartitions: 0
> > MaxPartitions: 3
> >
> > Further, here's my '/etc/stinit.def':
> >
> > manufacturer="IBM" model = "ULTRIUM-HH7" {
> > scsi2logical=1
> > can-bsr=1
> > auto-lock=1
> > two-fms=0
> > drive-buffering=1
> > buffer-writes
> > read-ahead=1
> > async-writes=1
> > can-partitions=1
> > fast-mteom=0
> > sysv=1
> > timeout=180
> > long-timeout=14400
> > mode1 blocksize=32768 compression=1
> > mode2 blocksize=32768 compression=0
> > mode3 disabled=1
> > mode4 disabled=1
> >
> > Sorry, about that!
> >
> > On 2018-01-11 02:43 PM, Luc Lalonde wrote:
> >> Hello Folks,
> >>
> >> I'm wondering if there's a bug with 'Amtapetype' (version 3.5.1).
> >>
> >> We're migrating from LTO5 to LTO7 and I'm getting strange results
> >> when I run 'amtapetype'.
> >>
> >> Here's what I get after roughly 35 hours:
> >>
> >> define tapetype LTO7 {
> >> comment "Created by amtapetype; compression enabled"
> >> length 5874932832 kbytes
> >> filemark 1813 kbytes
> >> speed 118310 kps
> >> blocksize 32 kbytes
> >> }
> >>
> >> Why is it saying that it can write roughly 6Tb if it's supposedly
> >> hardware compressed? LTO7 is supposed to give a compression ration
> >> of 2.5 to 1.
> >>
> >> I've disabled compression... Here's the ouptut of 'tapeinfo:
> >>
> >> [root@ulysses ~]# tapeinfo -f /dev/sg12
> >> Product Type: Tape Drive
> >> Vendor ID: 'IBM '
> >> Product ID: 'ULTRIUM-HH7 '
> >> Revision: 'G9Q1'
> >> Attached Changer API: No
> >> SerialNumber: '123456789A'
> >> MinBlock: 1
> >> MaxBlock: 8388608
> >> SCSI ID: 4
> >> SCSI LUN: 0
> >> Ready: yes
> >> BufferedMode: yes
> >> Medium Type: 0x78
> >> Density Code: 0x5c
> >> BlockSize: 32768
> >> DataCompEnabled: yes
> >> DataCompCapable: yes
> >> DataDeCompEnabled: yes
> >> CompType: 0xff
> >> DeCompType: 0xff
> >> Block Position: 2
> >> Partition 0 Remaining Kbytes: -1
> >> Partition 0 Size in Kbytes: -1
> >> ActivePartition: 0
> >> EarlyWarningSize: 0
> >> NumPartitions: 0
> >> MaxPartitions: 3
> >>
> >> Am I missing something?
> >>
> >> Thanks!|
> >>
> >
>
>
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