Hp StoreAll Storage User Manual download pdf (Page 160)

Using hard links with WORM files

You can use the Linux ln command without the -s option to create a hard link to a normal

(non-WORM) file on an retention-enabled file system. If you later make the file a WORM file, the

following restrictions apply until the file is deleted:

• You cannot make any new hard links to the file. Doing this would increment the metadata of

the link count in the file's inode, which is not allowed under WORM rules.

• You can delete hard links (the original file system entry or a hard-link entry) without deleting

the other file system entries or the file itself. WORM rules allow the link count to be

decremented.

Using remote replication

When using remote replication for file systems enabled for retention, the following requirements

must be met:

• The source and target file systems must use the same retention mode (Enterprise or Relaxed).

• The default, maximum, and minimum retention periods must be the same on the source and

target file systems.

• A clock synchronization tool such as ntpd must be used on the source and target clusters. If

the clock times are not in sync, file retention periods might not be handled correctly.

Also note the following:

• Multiple hard links on retained files on the replication source are not replicated. Only the first

hard link encountered by remote replication is replicated, and any additional hard links are

not replicated. (The retainability attributes on the file on the target prevent the creation of any

additional hard links). For this reason, HP strongly recommends that you do not create hard

links on retained files.

• For continuous remote replication, if a file is replicated as retained, but later its retainability

is removed on the source file system (using data retention management commands), the new

file’s attributes and any additional changes to that file will fail to replicate. This is because of

the retainability attributes that the file already has on the target, which will cause the file system

on the target to prevent remote replication from changing it.

• When a legal hold is applied to a file, the legal hold is not replicated on the target. If the file

on the target should have a legal hold, you will also need to set the legal hold on that file.

• If a file has been replicated to a target and you then change the file's retention expiration

time with the ibrix_reten_adm -e command, the new expiration time is not replicated to

the target. If necessary, also change the file's retention expiration time on the target.

Backup support for data retention

The supported method for backing up and restoring WORM/retained files is to use NDMP with

DMA applications. Other backup methods will back up the file data, but will lose the retention

configuration.

Troubleshooting data retention

Limitation on remote replication of retention-enabled file systems

When there is a large I/O load on the source file system and the auto-commit period is set to a

lower value, the following errors will display in the CRR logs:

• Partial transfer: ibrcfrworker returned error 23 (Partial transfer), which

can be expected in retention-enabled (WORM) environments when CRR cannot modify a

160 Managing data retention

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