If you are sending blocks of zeros to a tape drive, it is useless to compare speeds to anything that sends real data. Zero data input to most tape drives is almost completely optimized (compressed) out, so one gets very large, unrealistic speeds. Try sending random data then you will get a better idea of how fast the drive actually can write.
Best regards,
Kern
In regard to possible compression 360MB/sec seems slow for a spool drive serving an LTO-7. This is data from an 8 drive RAID 6 DELL box (PERC730P):
root@pangaea:~# dd if=/dev/zero of=/dev/null bs=1M count=32000
33554432000 bytes (34 GB, 31 GiB) copied, 1.89847 s, 17.7 GB/s
root@pangaea:~# dd if=/dev/zero of=test.zero bs=1M count=32000 conv=fsync
33554432000 bytes (34 GB, 31 GiB) copied, 29.3056 s, 1.1 GB/s
root@pangaea:~# dd if=test.zero of=/dev/null bs=1M
33554432000 bytes (34 GB, 31 GiB) copied, 27.9066 s, 1.2 GB/s
root@pangaea:~# tapeinfo -f /dev/nst0
Product Type: Tape Drive
Vendor ID: 'IBM '
Product ID: 'ULTRIUM-HH7 '
Revision: 'K4K1'
Attached Changer API: No
SerialNumber: '10WT141102'
MinBlock: 1
MaxBlock: 8388608
SCSI ID: 0
SCSI LUN: 0
Ready: yes
BufferedMode: yes
Medium Type: 0x78
Density Code: 0x5c
BlockSize: 0
DataCompEnabled: yes
DataCompCapable: yes
DataDeCompEnabled: yes
CompType: 0xff
DeCompType: 0xff
Block Position: 5264131
Partition 0 Remaining Kbytes: -1
Partition 0 Size in Kbytes: -1
ActivePartition: 0
EarlyWarningSize: 0
NumPartitions: 0
MaxPartitions: 3
Device {
Name = IBM-LTO7
Media Type = LTO
Archive Device = /dev/nst0
Automatic Mount = yes
Always Open = yes
Removable Media = yes
Random Access = no
Maximum Spool Size = 256GB
Spool Directory = /home/bacula/spool
Maximum File Size = 32GB
# Maximum Block Size = 524288
Maximum Block Size = 1048576
Backward Space File = yes
Fast Forward Space File = yes
}
19-Apr 16:46 pangaea-dir JobId 1466: Start Backup JobId 1466, Job=srv.2021-04-19_16.00.00_05
19-Apr 16:46 pangaea-dir JobId 1466: Using Device "IBM-LTO7" to write.
19-Apr 16:46 pangaea-sd JobId 1466: Spooling data ...
19-Apr 17:10 pangaea-sd JobId 1466: User specified Device spool size reached: DevSpoolSize=256,000,176,844 MaxDevSpoolSize=256,000,000,000
19-Apr 17:10 pangaea-sd JobId 1466: Writing spooled data to Volume. Despooling 256,000,176,844 bytes ...
19-Apr 17:26 pangaea-sd JobId 1466: Despooling elapsed time = 00:15:54, Transfer rate = 268.3 M Bytes/second
19-Apr 17:26 pangaea-sd JobId 1466: Spooling data again ...
19-Apr 17:52 pangaea-sd JobId 1466: User specified Device spool size reached: DevSpoolSize=256,000,176,881 MaxDevSpoolSize=256,000,000,000
19-Apr 17:52 pangaea-sd JobId 1466: Writing spooled data to Volume. Despooling 256,000,176,881 bytes ...
19-Apr 18:08 pangaea-sd JobId 1466: Despooling elapsed time = 00:16:13, Transfer rate = 263.1 M Bytes/second
19-Apr 18:08 pangaea-sd JobId 1466: Spooling data again ...
19-Apr 18:16 pangaea-sd JobId 1466: Committing spooled data to Volume "G-0620-6". Despooling 56,071,784,596 bytes ...
19-Apr 18:19 pangaea-sd JobId 1466: Despooling elapsed time = 00:03:04, Transfer rate = 304.7 M Bytes/second
19-Apr 18:19 pangaea-sd JobId 1466: Elapsed time=01:32:46, Transfer rate=102.0 M Bytes/second
19-Apr 18:19 pangaea-sd JobId 1466: Sending spooled attrs to the Director. Despooling 6,326 bytes ...
19-Apr 18:19 pangaea-dir JobId 1466: Bacula pangaea-dir 9.6.7 (10Dec20):
HTH, Udo
Am 21.04.21 um 09:14 schrieb fk+bacula--- via Bacula-users:
Hello there,
I'm using a Quantum LTO-7 HH drive with Ultrium LTO-7 tapes.
The streamer is connected on a SAS HAB microsemi 1100-4i.I set the Maximum block size = 524288
and run: speed file_size=3 skip_raw
with zero data and bacula block structure Total Write rate = 311.7 MB/s
with random data: Total Write rate = 94.74 MB/sFor backup I use the spooling function. Two SATA hdd's are build a RAID-0 (stripe) array.
This array is used for holding the spooling data (spool directory)
testing:
**** write test ****
dd if=/dev/zero of=/backup_spool/testfile bs=1M count=204800 conv=fdatasync,notrunc
204800+0 Datensätze ein
204800+0 Datensätze aus
214748364800 bytes (215 GB, 200 GiB) copied, 596,839 s, 360 MB/s
**** read test ****
dd if=/backup_spool/testfile of=/dev/null bs=1M count=204800
204800+0 Datensätze ein
204800+0 Datensätze aus
214748364800 bytes (215 GB, 200 GiB) copied, 625,029 s, 344 MB/sHave made test backup (1,1 TByte) and have monitored a constant write rate of 200 MByte/s during despooling.
Are the write values of the tape drive OK for a LTO-7 environment?
Thanks for any hints, Frank
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