# Fdbbackup files smaller than the actual storage size of the original database

**URL:** <https://forums.foundationdb.org/t/fdbbackup-files-smaller-than-the-actual-storage-size-of-the-original-database/4642>\
**Category:** Using FoundationDB\
**Created:** [October 2, 2024, 8:31am UTC](https://forums.foundationdb.org/t/fdbbackup-files-smaller-than-the-actual-storage-size-of-the-original-database/4642 "2024-10-02T08:31:16Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![418572](https://avatars.discourse-cdn.com/v4/letter/4/b782af/32.png) [@418572](https://forums.foundationdb.org/u/418572)\
**Post date:** [October 2, 2024, 8:31am UTC](https://forums.foundationdb.org/t/fdbbackup-files-smaller-than-the-actual-storage-size-of-the-original-database/4642/1 "2024-10-02T08:31:16Z")

</div>

through command status details in origin database:  
Data:  
Replication health - Healthy  
Moving data - 0.000 GB  
Sum of key-value sizes - 20 MB

but the size of the kvranges in the backup file generated by the fdbbackup command is noticeably smaller than the actual storage size of the original database (the result obtained from the status details command). However, there were no errors reported during the execution of the backup process.

fdbbackup start -C /mnt/config-volume/cluster-file -d ‘file:///home/backup’ --log  
The backup on tag `default’ was successfully submitted.

then  
fdbbackup status -C /mnt/config-volume/cluster-file:  
The previous backup on tag `default’ at file:///home/backup/backup-2024-09-30-03-44-54.440029 completed at version 6292909345356.  
BackupUID: 906a2085c6b1bdfab79cd4f18f0fbbe5  
BackupURL: file:///home/backup/backup-2024-09-30-03-44-54.440029

In the directory of the file named “backup-2024-09-30-03-44-54.440029”, there are three subdirectories:  
kvranges logs snapshots  
the kvrange size is only 1.3M which is noticeably smaller than 20M  
[root@fdb-backup-agent-6cb5b6bdc7-p8xnx kvranges]# ls  
snapshot.000006292889345357  
[root@fdb-backup-agent-6cb5b6bdc7-p8xnx kvranges]# cd snapshot.000006292889345357/  
[root@fdb-backup-agent-6cb5b6bdc7-p8xnx snapshot.000006292889345357]# ls  
0  
[root@fdb-backup-agent-6cb5b6bdc7-p8xnx snapshot.000006292889345357]# cd 0/  
[root@fdb-backup-agent-6cb5b6bdc7-p8xnx 0]# ls  
range,6292889377357,492f54d441e06f9144136b723ee28824,1048576  
[root@fdb-backup-agent-6cb5b6bdc7-p8xnx 0]# ls -lh  
total 1.3M  
-rw-r–r–. 1 root root 1.3M Sep 30 03:44 range,6292889377357,492f54d441e06f9144136b723ee28824,1048576

---

<div class="post-metadata">

**Author:** ![418572](https://avatars.discourse-cdn.com/v4/letter/4/b782af/32.png) [@418572](https://forums.foundationdb.org/u/418572)\
**Post date:** [October 2, 2024, 10:02am UTC](https://forums.foundationdb.org/t/fdbbackup-files-smaller-than-the-actual-storage-size-of-the-original-database/4642/2 "2024-10-02T10:02:46Z")

</div>

I have very little knowledge about FoundationDB, I just want to back up all the data at the current time

---

<div class="post-metadata">

**Author:** ![418572](https://avatars.discourse-cdn.com/v4/letter/4/b782af/32.png) [@418572](https://forums.foundationdb.org/u/418572)\
**Post date:** [October 2, 2024, 11:09am UTC](https://forums.foundationdb.org/t/fdbbackup-files-smaller-than-the-actual-storage-size-of-the-original-database/4642/3 "2024-10-02T11:09:29Z")

</div>

foundationdb version is 7.1.15 and backup\_agent pod version is same

---

<div class="post-metadata">

**Author:** ![jzhou](https://sea1.discourse-cdn.com/foundationdb/user_avatar/forums.foundationdb.org/jzhou/32/445_2.png) [@jzhou](https://forums.foundationdb.org/u/jzhou)\
**Post date:** [October 3, 2024, 3:34pm UTC](https://forums.foundationdb.org/t/fdbbackup-files-smaller-than-the-actual-storage-size-of-the-original-database/4642/4 "2024-10-03T15:34:23Z")

</div>

Since your DB is small, you can dump all the key value pairs and calculate their sizes, e.g., `fdbcli --exec getrange "" \xff 10000000000`. The third parameter is the number of keys. Because of 5s limit, you may not read all keys at once and you may need to resume from the last key read. Most likely the total size is about 1.3M. Then you can check keys in the system keyspace, i.e., `\xff` to `\xff\xff` and its size.

Another thing to check is if you have multiple backup agents running, each one will write backup files. So the total should be counting all output files.

---

<div class="post-metadata">

**Author:** ![418572](https://avatars.discourse-cdn.com/v4/letter/4/b782af/32.png) [@418572](https://forums.foundationdb.org/u/418572)\
**Post date:** [October 8, 2024, 2:09am UTC](https://forums.foundationdb.org/t/fdbbackup-files-smaller-than-the-actual-storage-size-of-the-original-database/4642/5 "2024-10-08T02:09:28Z")

</div>

> [@jzhou](#):
>
> Since your DB is small, you can dump all the key value pairs and calculate their sizes, e.g., `fdbcli --exec getrange "" \xff 10000000000`. The third parameter is the number of keys. Because of 5s limit, you may not read all keys at once and you may need to resume from the last key read. Most likely the total size is about 1.3M. Then you can check keys in the system keyspace, i.e., `\xff` to `\xff\xff` and its size

thanks for your reply, but status details command shows  
Data:  
Replication health - Healthy  
Moving data - 0.000 GB  
Sum of key-value sizes - 22 MB  
Disk space used - 526 MB

---

<div class="post-metadata">

**Author:** ![418572](https://avatars.discourse-cdn.com/v4/letter/4/b782af/32.png) [@418572](https://forums.foundationdb.org/u/418572)\
**Post date:** [October 8, 2024, 3:44am UTC](https://forums.foundationdb.org/t/fdbbackup-files-smaller-than-the-actual-storage-size-of-the-original-database/4642/6 "2024-10-08T03:44:48Z")

</div>

These are the last few lines of the log file from executing the fdbbackup command, where a usage rate reaches one hundred percent, and I’m not sure what it means.

```auto
<Event Severity="10" Time="1728358698.677631" DateTime="2024-10-08T03:38:18Z" Type="FastAllocMemoryUsage" ID="0000000000000000" TotalMemory="917472" UnusedMemory="0" Utilization="100.000000%" ThreadID="2510434358476276060" Machine="172.22.25.33:266" LogGroup="default" ClientDescription="primary-7.1.15-2510434358476276060" />
<Event Severity="10" Time="1728358698.677631" DateTime="2024-10-08T03:38:18Z" Type="NetworkMetrics" ID="0000000000000000" Elapsed="0.51311" CantSleep="0" WontSleep="2" Yields="1" YieldCalls="17" YieldCallsTrue="0" RunLoopProfilingSignals="1" YieldBigStack="0" RunLoopIterations="54" TimersExecuted="62" TasksExecuted="89" ASIOEventsProcessed="84" ReadCalls="39" WriteCalls="16" ReadProbes="22" WriteProbes="0" PacketsRead="19" PacketsGenerated="20" WouldBlock="22" LaunchTime="8.10623e-06" ReactTime="7.08103e-05" DCID="[not set]" ZoneID="[not set]" MachineID="[not set]" SlowTask1M="1" PriorityBusy0="0.507966" PriorityStarvedBelow1="0.00290251" PriorityMaxStarvedBelow1="0.000918865" PriorityStarvedBelow3500="0.00290251" PriorityMaxStarvedBelow3500="0.000918865" PriorityStarvedBelow7000="0.00266075" PriorityMaxStarvedBelow7000="0.000918865" PriorityStarvedBelow7500="0.00221038" PriorityMaxStarvedBelow7500="0.000838995" PriorityStarvedBelow8500="0.00152445" PriorityMaxStarvedBelow8500="0.000838995" PriorityStarvedBelow8900="0.000720739" PriorityMaxStarvedBelow8900="8.17776e-05" PriorityStarvedBelow10500="0.000125647" PriorityMaxStarvedBelow10500="6.8903e-05" ThreadID="2510434358476276060" Machine="172.22.25.33:266" LogGroup="default" ClientDescription="primary-7.1.15-2510434358476276060" TrackLatestType="Original" />
<Event Severity="10" Time="1728358698.677631" DateTime="2024-10-08T03:38:18Z" Type="MachineMetrics" ID="0000000000000000" Elapsed="0.51311" MbpsSent="2.72627" MbpsReceived="17.0646" OutSegs="309" RetransSegs="0" CPUSeconds="0.0254015" TotalMemory="8188428288" CommittedMemory="2482495488" AvailableMemory="5705932800" DCID="[not set]" ZoneID="[not set]" MachineID="[not set]" ThreadID="2510434358476276060" Machine="172.22.25.33:266" LogGroup="default" ClientDescription="primary-7.1.15-2510434358476276060" TrackLatestType="Original" />

```

---

<div class="post-metadata">

**Author:** ![SteavedHams](https://sea1.discourse-cdn.com/foundationdb/user_avatar/forums.foundationdb.org/steavedhams/32/18_2.png) [@SteavedHams](https://forums.foundationdb.org/u/SteavedHams)\
**Post date:** [October 8, 2024, 9:41pm UTC](https://forums.foundationdb.org/t/fdbbackup-files-smaller-than-the-actual-storage-size-of-the-original-database/4642/7 "2024-10-08T21:41:36Z")

</div>

`Sum of key-value sizes` is only an estimate and it includes the FDB internal system keyspace (keys starting with `\xff`) which is not written to the backup.