amtapetype report the drive is in compressed mode because it can write
compressible data a lot faster than uncompressible data.
amtapetpye write uncompressible data to determine the size, that's why
you get the native tape size.
It is also strange that it report 'LEOM is not supported', i'm sure LEON
is supported for theses drives.
Jean-Louis
On 13/01/18 04:48 PM, Luc Lalonde wrote:
Hello Jean-Louis,
I re-ran ‘amtapetype’ with a much larger blocksize (512k). Here’s the
result:
Checking for FSF_AFTER_FILEMARK requirement
Applying heuristic check for compression.
Wrote random (uncompressible) data at 139266114.064516 bytes/sec
Wrote fixed (compressible) data at 287816635.733333 bytes/sec
Compression: enabled
Writing one file to fill the volume.
Wrote 6017046282240 bytes at 138187 kb/sec
Writing smaller files (60170436608 bytes) to determine filemark.
define tapetype unknown-tapetype {
comment "Created by amtapetype; compression enabled"
length 5876021760 kbytes
filemark 2839 kbytes
speed 138187 kps
blocksize 512 kbytes
}
# LEOM is not supported for this drive and kernel
After having unloaded and re-loaded this tape, I can confirm that the
compression is disabled:
DataCompEnabled: no
DataCompCapable: yes
DataDeCompEnabled: yes
As I mentioned in my earlier mail, the compression test does not seem
to be correctly reporting the compression status of the tape… The
‘length’ reported with ‘amtapetype’ is roughly the ‘native’ capacity
of the LTO7 tapes.
Can you confirm this?
Best regards, Luc.
On Jan 11, 2018, at 3:09 PM, Jean-Louis Martineau
<jmartin...@carbonite.com <mailto: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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