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Data Domain mtree limit?
We have created a approx. 80 NFS/CIFS on DD.
We went to create another and received a message: Maximum number of MTrees reached.
What is this number and how do we get around it?
Each share has its own mtree.
Should we find a way to consolidate?
James_Ford
30 Posts
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February 22nd, 2016 06:00
So let me try and describe this further:
- Each DDR/DDVE runs a single instance of the DDFS file system
- When created DDFS will contain 1 mtree (/data/col1/backup)
- You can create additional mtrees using the 'mtree create' command
- You can delete mtrees (and all data they contain) with the 'mtree delete' command (the mtree is not physically removed until the next clean is run)
- Additional mtrees are normally created/used to divide logical data sets being written to the DDR - for example:
Each VTL pool will be a separate mtree
Each DDBoost logical storage unit (LSU) will be a separate mtree
Each Avamar grid writing to the DDR will have its own mtree
- Basically each individual application tends to use its own mtree to provide logical data separation
- Note that there is no physical separation of data between mtrees - data written to one mtree still de-duplicates against data in all other mtrees - mtrees offer logical separation only
- The advantage of using multiple mtrees is that:
It makes the DDR easier to administer - you immediately know what type of data/backups are in each mtree and you can see the amount of data written and its de-dupe rate for each individual mtree
Mtrees can be individually replicated - for example this means you can replicate data in /data/col1/mtree1 to destination DDR 1, data in /data/col1/mtree2 to destination DDR 2, and not replicate data in /data/col1/mtree3 at all
Point in time snapshots and so on are created against an mtree and not the whole file system
You can enable/use features such as retention lock against a single or subset of mtrees
If using extended retention (not applicable to DDVE) you can set different migration policies against different mtrees
and so on
- The number of individual mtrees supported on a DDR depends on platform type - as of 5.7 DDVE supports 100 mtrees, i.e.:
# mtree create /data/col1/newmtree
**** Maximum number of MTrees reached.
From BASH mode we can see that this is because 100 mtrees already exist (note that BASH mode is not accessible to customers):
!!!! DDVE_57_JF YOUR DATA IS IN DANGER !!!! # ddsh -a mtree list | grep /data/col1 | wc -l
100
- Within each mtree you can still create subdirectories:
# find /data/col1/testmtree1 -type d
/data/col1/testmtree1
/data/col1/testmtree1/directory1
/data/col1/testmtree1/directory2
/data/col1/testmtree1/directory3
/data/col1/testmtree1/directory4
/data/col1/testmtree1/directory5
#
- CIFS shares/NFS exports can be created against an mtree OR a subdirectory of an mtree - for example creating an NFS export against an mtree:
# nfs add /data/col1/testmtree1 DDVE_57_JF.localdomain
NFS export for "/data/col1/testmtree1" added.
And creating against a subdirectory in an mtree:
# ddsh -a nfs add /data/col1/testmtree1/directory3 DDVE_57_JF.localdomain
NFS export for "/data/col1/testmtree1/directory3" added.
DDRs support many more than 100 CIFS shares/NFS exports (however I do not have the exact number to hand)
- It is not necessary to create a separate mtree for each CIFS/NFS share
- In normal usage where mtrees are used to logically separate backup/data type it is common to see a hand full of mtrees however unless the DDR is a large/complex system it is very unusual to see them hitting their limit of configured mtrees
I hope this helps.
Druehl1
223 Posts
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February 18th, 2016 23:00
Hello,
it depends on the Data Domain system and the DDOS version you have.
Here is a screenshot from DDOS 5.7.0.10 release notes.
Mtrees are only a kind of folder in the Data Domain filesystem. One Mtree per NFS/CIFS share has advanteges when you are replicating Data Domain systems per Mtree or want to see dedup ratios per Mtree.
Otherwise you altough can create more NFS/CIFS shares per Mtree.
James_Ford
30 Posts
1
February 24th, 2016 07:00
The deleted mtree will still physically exist until you run clean on the DDR – clean deletes the mtree prior to phase 1 then frees any underlying disk space used by data in the mtree in subsequent phases. Can you try running clean then see if you can create a new mtree?
dstarm
124 Posts
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February 24th, 2016 07:00
James. Thank you! That was what I was hoping for and that is what worked!
dstarm
124 Posts
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February 24th, 2016 07:00
I deleted an Mtree and have 99 displayed (was 100) I tried to create a new one to begin consolidating and I am still getting max Mtree message. I refreshed several times.
is there something I am missing.
James_Ford
30 Posts
0
February 24th, 2016 07:00
No problem – glad I could help ☺