expand raid 10?

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bhom920
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expand raid 10?

Post by bhom920 » Sun Mar 18, 2018 9:55 am

So i currently have a TVS-1272 and was wondering could i expand an existing raid 10 (4 x 6tb) for additional storage without affecting the existing data by installing an additional 2 x 6tb?

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Don
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Re: expand raid 10?

Post by Don » Sun Mar 18, 2018 10:11 am

I don’t think so but check the manual for your expansion options.
Read the Online Manuals and use the forum search feature before posting.

It is a recommended to use RAID and have external backups. RAID will protect you from disk failure, keep your system running, and data accessible while the disk is replaced and the RAID rebuilt. Backups will allow you to recover data that is lost or corrupted, or from system failure. One does not replace the other.

Submit bugs and feature requests to QNAP via their Helpdesk app.

NAS: TVS-882BR | F/W: 4.3.6.0895 | 40GB | 2 x M.2 SATA RAID 1 (System/VMs) | 4 x M.2 NMVe QM2-4P-384A RAID 5 (Cache) | 5 x 4TB HDD RAID 6 (Data) | 1 x Blu-ray
NAS: TVS-663 | F/W: 4.4.1.1086 | 16GB | 2 x M.2 NMVe QM2-2P RAID 1 (Cache) | 4 x 4TB RAID 5
Apps: Boinc, Squid, DNSMasq, PLEX, iDrive, QVPN, QLMS, MP3fs, HBS, Entware, DLstation, +others

P3R
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Re: expand raid 10?

Post by P3R » Mon Mar 19, 2018 8:55 pm

bhom920 wrote:So i currently have a TVS-1272...
I can't find that model. Maybe you mean a TVS-1282 or TVS-1271U?
...was wondering could i expand an existing raid 10 (4 x 6tb) for additional storage without affecting the existing data by installing an additional 2 x 6tb?
No, that's one of the disadvantages for RAID 10 compared to RAID 5 and RAID 6.

From the manual:
Note: New disks cannot be inserted into existing RAID groups for specific RAID types, such as, RAID 0, RAID 10, Single, or JBOD. You must create additional RAID groups to expand these storage pools.

If using storage pools you could add the two additional disks as a RAID 1 group to the pool but it would be more of a workaround than a tecnically nice solution.

The better option would be to take this opportunity to switch from RAID 10 to RAID 6. That would give you better reliability and the possibility to do future storage expansion by adding disks. With RAID 6, disks don't have to be added in pairs but could be added one at a time for greater flexibility. Depending on the specific usage, performance may also improve with a switch to RAID 6.
RAID have never ever been a replacement for backups. Without backups on a different system (preferably placed at another site), you will eventually lose data!

A non-RAID configuration (including RAID 0, which isn't really RAID) with a backup on a separate media protects your data far better than any RAID-volume without backup.

All data storage consists of both the primary storage and the backups. It's your money and your data, spend the storage budget wisely or pay with your data!

bhom920
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Re: expand raid 10?

Post by bhom920 » Thu Mar 22, 2018 4:05 am

sorry yes i have a TVS-1271u. I chose raid10 over 6 for performance. I guess i will need to use up another 4 bays to expand. Thanks

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Don
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Re: expand raid 10?

Post by Don » Thu Mar 22, 2018 4:56 am

Rebuild from scratch and use RAID 6. RAID 10 offers no advantages over RAID 6 in modern systems. RAID can survive 2 failed disks. RAID 10 might survive 2 failed disks depending which 2 fail. RIAD 6 is expandable. RAID 10 is not. WIth newer systems RAID 10 offers little or no performance advantages.
Read the Online Manuals and use the forum search feature before posting.

It is a recommended to use RAID and have external backups. RAID will protect you from disk failure, keep your system running, and data accessible while the disk is replaced and the RAID rebuilt. Backups will allow you to recover data that is lost or corrupted, or from system failure. One does not replace the other.

Submit bugs and feature requests to QNAP via their Helpdesk app.

NAS: TVS-882BR | F/W: 4.3.6.0895 | 40GB | 2 x M.2 SATA RAID 1 (System/VMs) | 4 x M.2 NMVe QM2-4P-384A RAID 5 (Cache) | 5 x 4TB HDD RAID 6 (Data) | 1 x Blu-ray
NAS: TVS-663 | F/W: 4.4.1.1086 | 16GB | 2 x M.2 NMVe QM2-2P RAID 1 (Cache) | 4 x 4TB RAID 5
Apps: Boinc, Squid, DNSMasq, PLEX, iDrive, QVPN, QLMS, MP3fs, HBS, Entware, DLstation, +others

macsimcon
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Re: expand raid 10?

Post by macsimcon » Mon Aug 26, 2019 4:29 am

RAID 10 offers no advantages over RAID 6? RAID 10 writes three times faster than RAID 6, and when you need a rebuild, RAID 10 will be much faster. In fact, a rebuild in RAID 6 requires reading the parity data from the other drives in the RAID, which could cause an additional failure depending on how long it takes.

Have you tried rebuilding a RAID 6 array containing 8 TB, 10 TB, or 12 TB drives? It's going to take a long time, and the risk of additional drive failure(s) during the rebuild is significant.

P3R
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Re: expand raid 10?

Post by P3R » Mon Aug 26, 2019 5:28 am

macsimcon wrote:
Mon Aug 26, 2019 4:29 am
RAID 10 writes three times faster than RAID 6...
That may have been true in NASes 10 years ago but I'm pretty sure it isn't today. Do you have any testing on a modern Qnap to back that bold statement up?

I'd say that given a good CPU (as exist in the majority of NAS models today) RAID 6 actually writes faster than RAID 10 from 6 disks and up.

This is an example with a Qnap TS-1277 showing the best and worse result from 5 tests. It's a sequential write directly to the volume from within the NAS itself to make sure it's the storage we're testing and that the network doesn't affect the numbers.

4 disks in raid-6 237.71 MB/s 229.19 MB/s
5 disks in raid-6 339.16 MB/s 324.55 MB/s
6 disks in raid-6 437.33 MB/s 422.79 MB/s
7 disks in raid-6 525.60 MB/s 495.07 MB/s
8 disks in raid-6 606.99 MB/s 589.82 MB/s

4 disks in raid-10 247.34 MB/s 245.06 MB/s
6 disks in raid-10 362.25 MB/s 356.38 MB/s
8 disks in raid-10 478.31 MB/s 472.27 MB/s

The disks are very old (+9 years) and slow so don't focus on the relatively low figures. Since it's the same disk in all tests, it's the comparison between RAID 6 and RAID 10 with the same number of disks that's interesting.
...and when you need a rebuild, RAID 10 will be much faster.
True, the rebuild with RAID 10 is faster.

The RAID 10 will however need to read one disk to mirror it when rebuilding the replaced disk and that disk being read is exactly the one critical disk that isn't allowed to fail. If it does, the complete array is lost. There's no redundancy on that critical disk.
In fact, a rebuild in RAID 6 requires reading the parity data from the other drives in the RAID, which could cause an additional failure depending on how long it takes.
True again, but what you forget to mention is that RAID 6 still have disk redundancy during the rebuild so another (any) disk is allowed to fail without causing a disaster.

Check out a RAID reliability calculator (here's one example), RAID 6 is more reliable than RAID 10 up to very large numbers of disks despite having slower rebuilds.

To sum up:
  • RAID 6 offer more usable storage than RAID 10 (from 6 disks and up).
  • RAID 6 writes faster than RAID 10 (from 6 disks and up with a decent CPU).
  • RAID 6 is more reliable than RAID 10 (at least up to something like 13-14 disks).
  • RAID 6 can be expanded by adding disks, a RAID 10 is always stuck at the number of disks it started with (at least in a Qnap).
RAID have never ever been a replacement for backups. Without backups on a different system (preferably placed at another site), you will eventually lose data!

A non-RAID configuration (including RAID 0, which isn't really RAID) with a backup on a separate media protects your data far better than any RAID-volume without backup.

All data storage consists of both the primary storage and the backups. It's your money and your data, spend the storage budget wisely or pay with your data!

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