On 1/24/24 12:48, Marco Gaiarin wrote:
My new IBM LTO9 tape unit have a data sheet performace of:https://www.ibm.com/docs/it/ts4500-tape-library/1.10.0?topic=performance-lto-specifications so on worst case (compression disabled) seems to perform 400 MB/s on an LTO9 tape. Practically on Bacula i get 70-80 MB/s. I've just: 1) followed: https://www.bacula.org/9.6.x-manuals/en/problems/Testing_Your_Tape_Drive_Wit.html#SECTION00422000000000000000 getting 237.7 MB/s on random data (worst case). 2) checked disk performance (data came only from local disk); i've currently 3 servers, some perform better, some worster, but the best one have a read disk performance pretty decent, at least 200MB/s on random access (1500 MB/s on sequential one).
Disk that is local to the server does not mean it is local to the bacula-sd process or tape drive. If the connection is 1 gigabit Ethernet, then max rate is going to be 125 MB/s.
3) disabled data spooling, of course; as just stated, data came only from local disks. Enabled attribute spooling.
That is probably not what you want to do. You want the the bacula-sd process to spool data on its local disk so that when it is despooled to the tape drive it is reading only from local disk, not from a small RAM buffer that is being filled through a network socket. Even with a 10 G Ethernet network it is better to spool data for LTO tape drives, since the client itself might not be able to keep up with the tape drive, or is busy, or the network is congested, etc.
Clearly i can expect some performance penalty on Bacula and mixed files, but really 70MB/s are slow... What else can i tackle with? Thanks.
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