Question about JBOD

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sandro_rocha
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Question about JBOD

Post by sandro_rocha »

Good Morning. Ask me a question: if I put two disks on the NAS configured as JBOD and one of the disks is damaged, do I lose all data or just the data on the bad disk? I found dubious information that ended up making me think JBOD was a version of RAID 0 with no performance increase, that is, useless.
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father.mande
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Location: La Rochelle (France)

Re: Question about JBOD

Post by father.mande »

Hi,
sandro_rocha wrote:Good Morning. Ask me a question: if I put two disks on the NAS configured as JBOD and one of the disks is damaged, do I lose all data or just the data on the bad disk? I found dubious information that ended up making me think JBOD was a version of RAID 0 with no performance increase, that is, useless.
JBOD : Just a Bunch Of Disks don't interlace block as Raid0 ... so NO gain of performance, but if you lost a disk you lost all the files in this disk not in the others.
Problem is to know HOW the JBOD is filled
... some put files on the first disk up to some threshold then put next files on next disks
... some put files in different disks
BUT all put entire file in a disk (no split)

So you don't lost the files in the disks not failed ... but you don't know the files put in this disk ... so you lost some of them ... but ...

I prefer (but it's a choice) to have 2 singles disks and know where are my file (so able to get backup) than using JBOD ... without knowing where are physically the files ...

Even Raid is not a backup security is :
Raid0 NOTHING
JBOD partial but unknown list
Single partial but know folders (and share)
Raid1 security lost 1 disks
Raid5 more secure if you lost 1 disk
Raid6 more secure able to lost 2 disks
Raid 10 is a combination of Raid0 and Raid1 secure for one disk ... but dangerous

Philippe.
AS6602T / AS5202T /AS5002T / AS1002T / FS6706T
sandro_rocha
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Re: Question about JBOD

Post by sandro_rocha »

Thanks.
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Nazar78
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Re: Question about JBOD

Post by Nazar78 »

father.mande wrote:Raid 10 is a combination of Raid0 and Raid1 secure for one disk ... but dangerous
Hi Philippe,

Sorry I'm curious but why do you mentioned raid 10 is dangerous? It's minimum lost of 1 disk up to N/2 (each group fail 1 disk). Think it's security is ranked in between raid 5 and 6 but with superior reads mostly writes like raid 0 with exception of capacity lost?
AS5304T - 16GB DDR4 - ADM-OS modded on 2GB RAM
Internal:
- 4x10TB Toshiba RAID10 Ext4-Journal=Off
External 5 Bay USB3:
- 4x2TB Seagate modded RAID0 Btrfs-Compression
- 480GB Intel SSD for modded dm-cache (initramfs auto update patch) and Apps

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father.mande
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Re: Question about JBOD

Post by father.mande »

Hi,

It's just a VERY short response (to another subject) ... and doing a one word response open the discussion and different point of view :D (suppose it's an error :oops: )

Raid10 is dangerous especially when you used SOFTWARE Raid management, because any erroneous blocks (without checksum block in Raid 0 mode) can generate delay or crash in case of rebuild
Raid10 is very interesting for HARDWARE Raid management

In complement :
... Raid10 is reserved to specific request with very large number of users on large number of file (not for ex. for database in a large partition in direct access without file or to have best access to a media file ... read sequentially so more impacted by buffering and network capabilities.
... Raid0 add performance but also ONLY in some case ... when losing data or access in not a problem (cluster mode for ex.)
... with low speed disk (ex. 5900 TPM for NAS) ... that target 7/7 24/24 run and not pure performance ... Raid0 have very low to no interest.
... Raid0 / 10 can have performance problem if disks are not exactly the same (not brand but characteristics) ... up to loosing some block and generating retry
etc.

so I consider, but perhaps it's an error, that it's not the best usage (except for professional adding a fine analysis of they need), Generally it's offer to cover all the case, but I think that Asustor or other Brand don't really inform users of the reality / difficulty of the choice ... and let users to take the responsibility.

BUT also I admit that the discussion can be very large and require to be complete pages and pages of exchange to attack all aspect ... so be free to have your own opinion and used what you want ... you are the master in your castle :lol:
I promise also to avoid short response in the future ...

Philippe.
AS6602T / AS5202T /AS5002T / AS1002T / FS6706T
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Nazar78
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Re: Question about JBOD

Post by Nazar78 »

haha ok2 no harm done, yeah your explanation is always good.
AS5304T - 16GB DDR4 - ADM-OS modded on 2GB RAM
Internal:
- 4x10TB Toshiba RAID10 Ext4-Journal=Off
External 5 Bay USB3:
- 4x2TB Seagate modded RAID0 Btrfs-Compression
- 480GB Intel SSD for modded dm-cache (initramfs auto update patch) and Apps

When posting, consider checking the box "Notify me when a reply is posted" to get faster response
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