CLI Guide

Table Of Contents

Individual migrations may ask for confirmation when they start. Use the --force argument to suppress these requests for

confirmation.

Batch migrations across clusters can result in the following error:

VPlexcli:/> batch-migrate start /var/log/VPlex/cli/migrate.txt

The source device 'SveTest_tgt_r0_case2_1_0002' has a volume

'SveTest_tgt_r0_case2_1_0002_vol' in a view. Migrating to device

'SveTest_src_r0_case2_2_0002' will create a synchronous distributed device. In this GEO

system, this can increase the per I/O latency on 'SveTest_tgt_r0_case2_1_0002_vol'. If

applications using 'SveTest_tgt_r0_case2_1_0002_vol' are sensitive to this latency, they

may experience data unavailability. Do you wish to proceed ? (Yes/No) y

WARNING: Failed to start migration /clusters/cluster-1/devices/

SveTest_tgt_r0_case2_1_0002 --> /clusters/cluster-2/devices/SveTest_src_r0_case2_2_0002

: Evaluation of <<dm migration start -n BR0_0 -f /clusters/cluster-1/devices/

SveTest_tgt_r0_case2_1_0002 -t /clusters/cluster-2/devices/SveTest_src_r0_case2_2_0002

-s 128kB>> failed.

Failed to create a new data-migration.

Unable to attach mirror 'SveTest_src_r0_case2_2_0002' to distributed Device

'MIGRATE_BR0_0'.

Firmware command error.

Active metadata device does not have a free slot.

Started 0 of 1 migrations.

Refer to the troubleshooting section of the metro node procedures in the SolVe Desktop for instructions on increasing the

number of slots.

About transfer-size

Transfer-size is the size of the region in cache used to service the migration. The area is globally locked, read at the source, and

written at the target.

Transfer-size can be as small 40 K, as large as 128 M, and must be a multiple of 4 K. The default recommended value is 128 K.

A larger transfer-size results in higher performance for the migration, but may negatively impact front-end I/O. This is especially

true for metro node Metro migrations.

A smaller transfer-size results in lower performance for the migration, but creates less impact on front-end I/O and response

times for hosts.

Set a large transfer-size for migrations when the priority is data protection or migration performance. Set a smaller transfer-size

for migrations when the priority is front-end storage response time.

Factors to consider when specifying the transfer-size:

● For metro node Metro configurations with narrow inter-cluster bandwidth, set the transfer size lower so the migration does

not impact inter-cluster I/O.

● The region specified by transfer-size is locked during migration. Host I/O to or from that region is held. Set a smaller

transfer-size during periods of high host I/O.

● When a region of data is transferred, a broadcast is sent to the system. Smaller transfer-size mean more broadcasts, slowing

the migration.

Examples

VPlexcli:/> batch-migrate start --file BS0_19 --transfer-size 1M