Is it OK to use _ and : in snapshot names?

[NASbox]

I know it is syntactically OK to use _ and : in snapshot names, but is it likely to break anything in FreeNAS?

I'm writing an external backup utility and I'd like to make snapshots with the following format TANK/DATASET@__BKPVOLNAME:YYMMSS-HHMMSS so that they are easy to parse/scan for. Any good reason not to do so?

 

[Chris Moore]

Just my opinion, but I would stay away from the : .
I have been using - and _ ; they have given me zero problems but the : .
I worry too much that it could be an issue. I have not tested it.
Why do you want a : ?

 

[kdragon75]

underscores "_" should be fine but I would avoid any other special characters.

 

[Ericloewe]

https://wiki.openindiana.org/oi/ZFS+naming+conventions

You should be fine.

 

[NASbox]

https://wiki.openindiana.org/oi/ZFS+naming+conventions

You should be fine.

underscores "_" should be fine but I would avoid any other special characters.

Just my opinion, but I would stay away from the : .
I have been using - and _ ; they have given me zero problems but the : .
I worry too much that it could be an issue. I have not tested it.
Why do you want a : ?

@kdragon75 , @Chris Moore @Ericloewe - Thanks much for the reply...

@Ericloewe I saw the link you referred to, and tried it, so I know it's valid. I was more concerned about it maybe being reserved by FreeNAS code or some other reason I hadn't thought of. I know ':' can't be used on Windows, but I can't think of why I would want to, but I guess there is a remote chance that it might come back an bite me in the butt.

@Chris Moore in answer to your reply my main reason was aesthetics as ':' would be used in that position in a sentence so it makes sense) and to make it super unique for parsing. TANK/DATASET@__RMDISK01:180418-123242, but I can live with TANK/DATASET@__RMDISK01_180418-123242

I'm working on a "guided" removable backup utility that uses zfs send/receive.

The process is roughly:

I load the removable drive caddy into the box, type backup in a root shell, and the backup script:

• detects the drive
  
• imports the correct pool (Config parameter maps Ser# to Pool Name)
  
• based on the pool contents, the script knows what datasets to update
• (Adding a dataset to a backup volume would be another manual script)

For example if the disk contains BACKUPDRIVE01 and the following backup datasets.

• BACKUPDRIVE01/DATASET1
• BACKUPDRIVE01/DATASET2
• BACKUPDRIVE01/DATASET3

The backup script will then:

• search the backup drive for the last snapshot of BACKUPDRIVE01/DATASET1 ("BULAST")
• create a snapshot TANK/DATASET1@__RMDISK01_180418-123242 ("BUNEW")
  
• find the snapshot corresponding to "BULAST" in TANK/DATASET1 ("BUMARK")
• Differential zfs send TANK/DATASET1@BUMARK TANK/DATASET1@BUNEW | zfs receive BACKUPDRIVE01/DATASET1
  
• repeat for BACKUPDRIVE01/DATASET2, BACKUPDRIVE01/DATASET3
• scrub
• list backup drive contents and provide the option to delete old snapshot(s)
  (Deletions would be a manual decision based on space consumed/space available/changes made/data importance. I would likely delete most snapshots not created by the backup script and keep the current and last markers)
• Remove Deleted markers from TANK/DATASETn
  
• ask permission to zpool export BACKUPDRIVE01 (or do it later manually if I want to do another scrub or other housekeeping on the backup)

FYI the server is mostly library/archive data that don't change too much/too often, and daily backups.

 

[anmnz]

Snapshot names appear as directory names under .zfs/.

A long time ago I tracked down a nasty bug triggered by timestamp-based directory names containing colons. They were ending up in environment variables like PATH and LD_LIBRARY_PATH, whose parsing they break.

So I just wouldn't do that.

 

[NASbox]

Snapshot namea appear as directory names under .zfs/.

A long time ago I tracked down a nasty bug triggered by timestamp-based directory names containing colons. They were ending up in environment variables like PATH and LD_LIBRARY_PATH, whose parsing they break.

So I just wouldn't do that.

Thanks... that's what I was looking for - I definately won't do it.

 

[kdragon75]

From the FreeNAS smb4.conf file:

Code:

  veto files = /.snapshot/.windows/.mac/.zfs/

So I would avoid those too.

 

[NASbox]

/.snapshot/.windows/.mac/.zfs/

Not sure exactly what you mean - can you please clarify?
Do you mean avoid the strings .snapshot .windows .mac and .zfs?

 

[kdragon75]

Not sure exactly what you mean - can you please clarify?
Do you mean avoid the strings .snapshot .windows .mac and .zfs?

Yes, that.

 

[NASbox]

Good to know