| ascp4: Transferring from the Command Line with Ascp 4 |
152
Use the specified number of storage "write" threads (receiver only). Default: 2. To set "read" threads
on the sender, use
--read-threads
.
For transfers to object or HDFS storage, write threads cannot exceed the maximum number of
jobs that are configured for Trapd. Default: 15. To use more threads, open
/opt/aspera/etc/
trapd/trap.properties
on the server and set
aspera.session.upload.max-jobs
to a number larger than the number of write threads. For example,
# Number of jobs allowed to run in parallel for uploads.
# Default is 15
aspera.session.upload.max-jobs=50
-X
rexmsg_size
Limit the size of retransmission requests to no larger than the specified size, in bytes. Max: 1440.
-Z
dgram_size
Use the specified datagram size (MTU) for FASP transfers. Range: 296-65535 bytes. Default: the
detected path MTU.
As of version 3.3, datagram size can be specified on the server by setting
<datagram_size>
in
aspera.conf
. The server setting overrides the client setting, unless the client is using a version
of
ascp
that is older than 3.3, in which case the client setting is used. If the pre-3.3 client does not
set
-Z
, the datagram size is the discovered MTU and the server logs the message "LOG Peer client
doesn't support alternative datagram size".
Ascp 4 Transfers with Object Storage
Files that are transferred with object storage are sent in chunks through the Aspera Trapd service. By default,
ascp4
uses 64 KB chunks and Trapd uses 1 MB chunks; this mismatch in chunk size can cause
ascp4
transfers to fail.
To avoid this problem, take one of the following actions:
1.
Set the chunk size (in bytes) in the server's
aspera.conf
. This value is used by both
ascp4
and Trapd, so the
chunk sizes match.
To set a global chunk size, run the following command:
# asconfigurator -x
"set_node_data;transfer_protocol_options_chunk_size,
value
"
Where
value
is between 256 KB (262144 bytes) and 1 MB (1048576 bytes).
To set a chunk size for the user, run the following command:
# asconfigurator -x
"set_user_data;user_name,
username
;transfer_protocol_options_chunk_size,
value
"
2.
Set the chunk size in the client's
aspera.conf
to the Trapd chunk size.
If Trapd is using the default chunk size, run the following command to set the chunk size to 1 MB:
# asconfigurator -x
"set_node_data;transfer_protocol_options_chunk_size,1048576"
3.
Set the chunk size in the client command line.
Run the
ascp4
session with the chunk size setting:
--chunk-size=1048576
.
