Re: [Bacula-users] LTO-7 btape speed test

[Kern Sibbald]

Hello,

From my experience (up to LTO-5), using 524288 as a block size is a reasonable size.  However LTO-7 drives are even faster, so you might try some tests with Maximum block size = 1048576.  Some people recommend much larger sizes, but in my tests (LTO-5) there is little speed gain with even bigger block sizes, and according to a Quantum technical tape specialist, you might experience more errors.

Also you should set Maximum File Size = 5G or bigger.  This determines how often Bacula writes EOF marks, which really slow down writing.  The bigger Maximum File Size is the faster (in general) Bacula can stream to tape.  However, if you set it too big it will take longer to get a single file back.  Bacula can position quickly to a block boundary but must search within a block for any given file.  If you are restoring everything, then Bacula will only have to search on the first file to be restored -- all the rest of the files will be found sequentially.

Good luck.

Kern

On 4/21/21 9:14 AM, fk+bacula--- via Bacula-users wrote:

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/s

For 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/s

Have 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

_______________________________________________
Bacula-users mailing list
Bacula-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/bacula-users

_______________________________________________
Bacula-users mailing list
Bacula-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/bacula-users