The introduction by Qsan Technology for Disk Rebuild & Spare Disk of Network Storage

1. Disk Rebuild & Spare Disks
In Qsan Network Storage
QsanTechnology.com

2. RAID 0, RAID 1
(Performance) (Data Protection)
RAID 0 RAID 1
D Z D
C Y C
B X B
A W A
Write
AA WW AA AA
BB X
X B
B B
B
CC YY CC CC
DD Z
Z D
D D
D
2X write speed 1X write speed

3. RAID 0, RAID 1
(Performance) (Data Protection)
RAID 0 RAID 1
D Z D
C Y C
B X B
A W A
Read
AA WW AA AA
BB X
X B
B B
B
CC YY CC CC
DD Z
Z D
D D
D
2X Read Speed 2X Read Speed

4. RAID 5
RAID 5 (1 Parity Stripe) A Balance of
performance and protection
DATA
D1 C1 B1 A1 D1 C1 B1 A1
D2 C2 B2 A2 D2 C2 B2 A2
D3 C3 B3 A3 D3 C3 B3 A3
CALC
ULAT
ES
A1 A2 A3 Ap
B1 B2 Bp B3
C1 Cp C2 C3
Dp D1 D2 D3
CALCULATES

5. RAID 5
RAID 5 (1 Parity Stripe) A Balance of
performance and protection
DATA
D1 C1 B1 A1 D1 C1 B1 A1
D2 C2 B2 A2 D2 C2 B2 A2
D3 C3 B3 A3 D3 C3 B3 A3
A1 A2 A3 Ap
B1 B2 Bp B3 B3
C1 Cp C2 C3
Fails
Dp D1 D2 D3
CALCULATES

6. Comparison
RAID 0 RAID 1 RAID 5 RAID 6
Min. Disk # 2 2 3 4
Fault 0 N-1 1 2
Tolerance Disk
#
Space nX 1X (n-1)X (n-2)X
N: Disk numbers
X: Disk space
All Qsan RAID
systems support RAID
0, 1, 0+1. 5, 6, 10
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7. Degrade Mode
 When one or more physical disks in a RAID Group
failed or missing, if…
 Amount of healthy disks left in the RAID Group >= X , where
 X = 1 in RAID 1 (N disks)
 X = N-1 in RAID 3/5 (N disks)
 X = N-2 in RAID 6 (N disks)
 The RAID group enters Degraded Mode, waiting for failed
disks to be replaced/recovered.
 RAID 0 enters failed status directly.
 Else, the RAID Group fails, cannot be recovered.

8. Degrade Mode Test
 How many failed physical disks at most can you have
in a RAID group to keep data availability?
 RAID 5 of 3 disks
 RAID 0 of 2 disks
 RAID 1 of 2 disks
 RAID 6 of 4 disks

9. Degrade Mode Test
 How many failed physical disks at most can you have
in a RAID group to keep data availability?
 RAID 5 of 3 disks Answer: 1 disk
 RAID 0 of 2 disks Answer: 0 disk
 RAID 1 of 2 disks Answer: 1 disk
 RAID 6 of 4 disks Answer: 2 disk
Do you pass this test?

10. RAID Group Health Status
All disks in good condition
Healthy
Failed/Missing Disk Amount
Within tolerance amount
Rebuilding finished
Failed/Missing Disks
Replaced/Restored
Degraded Rebuilding
Failed/Missing Disk Amount
Failed/Missing Disk Amount
(including disks being rebuilt)
Exceeds tolerance amount
Exceeds tolerance amount
Failed

11. Rebuild Mode
 While Rebuilding is processing
 All VDs (virtual disk) in the same RG(RAID group) are to be rebuilt
 VDs are rebuilt in order
 DATA can still be accessed
 Slower Performance
 Frequent I/O while rebuilding affects rebuilding progress

12. RAID Failure
 Disks undetected
 Removed disks, bad connectors, unpowered disks
 Failed Disks
 Bad disk status reported from the disks
 More than 300 I/O retries accumulated in 10 minutes
 Replace the faulty disks with healthy ones
 Read Error?
 Does not necessarily indicate disk failure.
 Disks with read errors are more likely to fail.
 Rebooting the system clears the Read Error status.

13. Spare Disks
 What is a spare disk?
 Why do we need spare disks?
 Types of spare disks
 Global spare
 Dedicated spare
 Requirements?
 What do we need in the system to use this function?

14. Global Spare (GS)
 A disk that is assigned to be the spare disk of ANY RG
in need.
 Can be used by ANY degraded RG.
RG1 RG1 RG2 RG3
RG1 RG1 RG2 RG3
RG1 RG1 RG2 GS
RG1 RG1 RG2 GS

15. Global Spare (GS)
 A disk that is assigned to be the spare disk of ANY RG
in need.
 Can be used by ANY degraded RG.
Auto assign
RG1 RG1 RG2 RG3
RG1 RG1 RG2 RG3
RG1 RG1 RG2 GS
RG1 RG1 RG2 GS

16. Global Spare (GS)
 A disk that is assigned to be the spare disk of ANY RG
in need.
 Can be used by ANY degraded RG.
Auto assign
RG1 RG1 RG2 RG3
RG1 RG1 RG2 RG3
RG1 RG1 RG2 GS
RG1 RG1 RG2 GS
Auto assign

17. Dedicated Spare (DS)
 A disk that is assigned to be the spare disk of a
Dedicated RG.
 Used by the dedicated RG ONLY.
RG1 RG1 RG2 RG3
RG1 RG1 RG2 RG3
RG1 RG1 RG2 DS1
RG1 RG1 RG2 DS3

18. Dedicated Spare (DS)
 A disk that is assigned to be the spare disk of a
Dedicated RG.
 Used by the dedicated RG ONLY.
Auto assign
RG1 RG1 RG2 RG3
RG1 RG1 RG2 RG3
RG1 RG1 RG2 DS1
RG1 RG1 RG2 DS3

19. Dedicated Spare (DS)
 A disk that is assigned to be the spare disk of a
Dedicated RG.
 Used by the dedicated RG ONLY.
Auto assign
RG1 RG1 RG2 RG3
RG1 RG1 RG2 RG3
RG1 RG1 RG2 DS1
RG1 RG1 RG2 DS3
NOT allowed!!

20. TrioNAS LX U600Q
 Outstanding Performance  Advanced Protection
o Hardware RAID o Snapshot
o SSD caching o Volume clone
o Qsan Unified OS o Battery Backup Module
o AntiVirus
 Integrated Backup Solution  Storage Efficiency
o Amazon S3 Cloud backup o Thin Provisioning, DeDup, Compression
o Remote Replication o UnifiedAUTH
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21. AegisSAN LX P600Q (iSCSI)
 10GbE iSCSI-6G SAS High Availability Systems  Outstanding Performance
 Intel Xeon Dual core CPU, Intel® Ethernet  QiSOE (Qsan Hardware iSCSI
10GbE offload engine)
 Dual Active controllers, and full redundant  Up to 640K IOPS, up to 4,000
and hot-pluggable design MB/s throughput
 2x 10GbE + 2x 1GbE iSCSI ports per controller
 SBB form factor, 4U24/3U16/2U12/2U24
 Support RAID 0, 1, 0+1, 3, 5, 6, 10, 30, 50, 60,
JBOD, N-way mirror, online volume
expansion 21

22. AegisSAN LX F600Q (Fibre Channel)
 8GbE FC-6G SAS High Availability Systems  Outstanding Performance
 Intel Xeon Dual core CPU  Up to 650K IOPS, up to 5,000
 Dual Active controllers, and full redundant and MB/s throughput
hot-pluggable design
 4x 8G FC + 2x 1GbE iSCSI ports per controller
 SBB form factor, 4U24/3U16/2U12/2U24
 Support RAID 0, 1, 0+1, 3, 5, 6, 10, 30, 50, 60,
JBOD, N-way mirror, online volume expansion
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23. QsanTechnology.com
Sales@QsanTechnology.com
Thank you very much!