# Unable to read some data

**URL:** <https://discuss.dgraph.io/t/unable-to-read-some-data/11051>\
**Category:** Badger\
**Tags:** kind:bug\
**Created:** [October 21, 2020, 1:19am UTC](https://discuss.dgraph.io/t/unable-to-read-some-data/11051 "2020-10-21T01:19:22Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![KlotzAndrew](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/klotzandrew/32/5197_2.png) [@KlotzAndrew](https://discuss.dgraph.io/u/KlotzAndrew)\
**Post date:** [October 21, 2020, 1:19am UTC](https://discuss.dgraph.io/t/unable-to-read-some-data/11051/1 "2020-10-21T01:19:22Z")

</div>

### What version of Go are you using (`go version`)?

go version go1.14.4 linux/amd64

### What operating system are you using?

Ubuntu/Linux

### What version of Badger are you using?

v2.0.3 → v2.2007.2

### Does this issue reproduce with the latest master?

Not sure how to reproduce (sorry!)

### Steps to Reproduce the issue

Not clear how to repo, but I can provide details on the setup and stack trace to the panic. Maybe someone with more context on the code can understand what is causing the issue.

- Run badgerDB on a Linux host for months
- Small host CPU/memory, occasionally resource-starved. Small disk size and has run out of disk space a few times.
- Processing a write-heavy workload with TTL on entries

Started noticing some data is not accessible at specific keys (panic or error when trying to access)

### What Badger options were set?

WithCompression(options.None).  
WithMaxBfCacheSize(10 \* 1024).  
WithMaxCacheSize(0).  
WithValueLogFileSize(valueLogSize()).  
WithMaxTableSize(maxTableSize()).  
WithLoadBloomsOnOpen(false).  
WithKeepL0InMemory(false).  
WithNumLevelZeroTables(1).  
WithNumLevelZeroTablesStall(2).  
WithTruncate(true).  
WithValueLogLoadingMode(options.FileIO).  
WithTableLoadingMode(options.FileIO)

### What did you do?

Try accessing data with a key

### What did you expect to see?

The data

### What did you see instead?

Runtime panic from badgerDB source code on v2.03

```auto
line":"73","message":"[PANIC RECOVER] runtime error: slice bounds out of range [:768016] with capacity 1761 goroutine 2131853 [running]:\recover.go:71
 +0xee\npanic(0xd76bc0, 0xc009cbf420)\n\t/usr/local/go/src/runtime/panic.go:679
 +0x1b2\ngithub.com/dgraph-io/badger/v2.(*valueLog).Read(0xc0000acf60, 0x6ec00001755, 0xc01275973f, 0xc0200edc60, 0xc, 0x5522b3, 0x410c06, 0x0, 0x0, 0x1)\n\t/go/pkg/mod/github.com/dgraph-io/badger/v2@v2.0.3/value.go:1523
 +0x60c\ngithub.com/dgraph-io/badger/v2.(*Item).yieldItemValue(0xc01b7bd1e0, 0xc, 0xc00d849300, 0x0, 0x10, 0xc, 0x5522b3)\n\t/go/pkg/mod/github.com/dgraph-io/badger/v2@v2.0.3/iterator.go:170
 +0x11c\ngithub.com/dgraph-io/badger/v2.(*Item).ValueCopy(0xc01b7bd1e0, 0x16bcab0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)\n\t/go/pkg/mod/github.com/dgraph-io/badger/v2@v2.0.3/iterator.go:127

<application stack trace here>

```

Upgrading to v2.2007.2 gives another error, still unable to access data:

```auto
badger 2020/10/21 01:12:07 ERROR: Invalid read: vp: {Fid:5973 Len:1772 Offset:309696319}
badger 2020/10/21 01:12:07 ERROR: Unable to read: Key: [<key byte values here>], Version : 5579443,
				meta: 66, userMeta: 0

```

---

<div class="post-metadata">

**Author:** ![ibrahim](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/ibrahim/32/6387_2.png) [@ibrahim](https://discuss.dgraph.io/u/ibrahim)\
**Post date:** [October 23, 2020, 8:17am UTC](https://discuss.dgraph.io/t/unable-to-read-some-data/11051/4 "2020-10-23T08:17:13Z")

</div>

@Naman can you look into this?

---

<div class="post-metadata">

**Author:** ![Naman](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/naman/32/3498_2.png) [@Naman](https://discuss.dgraph.io/u/Naman)\
**Post date:** [October 28, 2020, 8:32am UTC](https://discuss.dgraph.io/t/unable-to-read-some-data/11051/7 "2020-10-28T08:32:11Z")

</div>

Hey @KlotzAndrew, thanks for reporting this.

- Can you please provide the memory specs of the machine as well?
- Also, can you check if all these are the options that you set? I see these versions don’t have options like `MaxBfCacheSize`.

---

<div class="post-metadata">

**Author:** ![KlotzAndrew](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/klotzandrew/32/5197_2.png) [@KlotzAndrew](https://discuss.dgraph.io/u/KlotzAndrew)\
**Post date:** [November 4, 2020, 11:37pm UTC](https://discuss.dgraph.io/t/unable-to-read-some-data/11051/8 "2020-11-04T23:37:41Z")

</div>

Hey! Thanks for taking a look

- Running on a Digital Ocean 1vCPU 2GB droplet

These settings changed updating versions otherwise, those settings are the full list

2.0.3 used:

```auto
WithMaxBfCacheSize(10 * 1024).
WithMaxCacheSize(0).

```

v2.2007.2 changed those 2 lines to:

```auto
WithBlockCacheSize(0).
WithIndexCacheSize(10 * 1024).

```