我正在用HP P410 256MBcaching控制器和RAID5 / 10中的4x消费级SSD（三星EVO 850）来体验奇怪的写入iops限制。 升级到HP P410控制器的最新固件（6.64）之后，问题仍然存在。
Iostat输出：
Device: rrqm/s wrqm/sr/sw/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sda 0.00 0.00 1.00 158.00 36.00 15631.00 197.07 12.16 75.84 6.00 76.28 6.30 100.10 158 writes/s and 100 % util. 我的hpacucli输出：
=> ctrl all show config detail Smart Array P410 in Slot 2 Bus Interface: PCI Slot: 2 Serial Number: PACCR9SYLZ34 Cache Serial Number: PACCQ9SYP5CK RAID 6 (ADG) Status: Disabled Controller Status: OK Hardware Revision: C Firmware Version: 6.62 Rebuild Priority: Medium Expand Priority: Medium Surface Scan Delay: 15 secs Surface Scan Mode: Idle Queue Depth: Automatic Monitor and Performance Delay: 60 min Elevator Sort: Enabled Degraded Performance Optimization: Disabled Inconsistency Repair Policy: Disabled Wait for Cache Room: Disabled Surface Analysis Inconsistency Notification: Disabled Post Prompt Timeout: 0 secs Cache Board Present: True Cache Status: OK Cache Ratio: 100% Read / 0% Write Drive Write Cache: Disabled Total Cache Size: 256 MB Total Cache Memory Available: 144 MB No-Battery Write Cache: Disabled Battery/Capacitor Count: 0 SATA NCQ Supported: True Array: A Interface Type: Solid State SATA Unused Space: 0 MB Status: OK Array Type: Data Logical Drive: 1 Size: 698.6 GB Fault Tolerance: RAID 5 Heads: 255 Sectors Per Track: 32 Cylinders: 65535 Strip Size: 256 KB Full Stripe Size: 768 KB Status: OK Caching: Enabled Parity Initialization Status: Initialization Failed Unique Identifier: 600508B1001C8929D0C6820FB103773E Disk Name: /dev/sda Mount Points: None Logical Drive Label: A516FD0DPACCR9SYLZ3435C0 Drive Type: Data physicaldrive 1I:1:1 Port: 1I Box: 1 Bay: 1 Status: OK Drive Type: Data Drive Interface Type: Solid State SATA Size: 250 GB Firmware Revision: EMT01B6Q Serial Number: S21PNSAG270000F Model: ATA Samsung SSD 850 SATA NCQ Capable: True SATA NCQ Enabled: True Current Temperature (C): 30 Maximum Temperature (C): 70 SSD Smart Trip Wearout: Not Supported PHY Count: 1 PHY Transfer Rate: 3.0Gbps physicaldrive 1I:1:2 Port: 1I Box: 1 Bay: 2 Status: OK Drive Type: Data Drive Interface Type: Solid State SATA Size: 250 GB Firmware Revision: EMT01B6Q Serial Number: S21PNSAG269993V Model: ATA Samsung SSD 850 SATA NCQ Capable: True SATA NCQ Enabled: True Current Temperature (C): 32 Maximum Temperature (C): 70 SSD Smart Trip Wearout: Not Supported PHY Count: 1 PHY Transfer Rate: 3.0Gbps physicaldrive 1I:1:3 Port: 1I Box: 1 Bay: 3 Status: OK Drive Type: Data Drive Interface Type: Solid State SATA Size: 250 GB Firmware Revision: EMT01B6Q Serial Number: S21PNSAG269984Z Model: ATA Samsung SSD 850 SATA NCQ Capable: True SATA NCQ Enabled: True Current Temperature (C): 31 Maximum Temperature (C): 70 SSD Smart Trip Wearout: Not Supported PHY Count: 1 PHY Transfer Rate: 3.0Gbps physicaldrive 1I:1:4 Port: 1I Box: 1 Bay: 4 Status: OK Drive Type: Data Drive Interface Type: Solid State SATA Size: 250 GB Firmware Revision: EMT01B6Q Serial Number: S21PNSAG269998N Model: ATA Samsung SSD 850 SATA NCQ Capable: True SATA NCQ Enabled: True Current Temperature (C): 31 Maximum Temperature (C): 70 SSD Smart Trip Wearout: Not Supported PHY Count: 1 PHY Transfer Rate: 3.0Gbps SEP (Vendor ID PMCSIERA, Model SRC 8x6G) 250 Device Number: 250 Firmware Version: RevC WWID: 500143800694906F Vendor ID: PMCSIERA Model: SRC 8x6G
有人经历过HP P410的这个问题吗？
这里有几个问题。
hpssacli输出，您的RAID5奇偶校验初始化失败 。 Parity Initialization Status: Initialization Failed
这里列出了惠普在该控制器上固态硬盘的最佳实践 。
另请参阅： 使用RAID 10时 ， SSD（Intel 530）的读/写速度非常慢， HP ACU显示Smart Array控制器上的奇偶校验初始化失败
MLC SSD确实需要一个快速的专用DRAMcaching来提供较高的IOPS值。
当您的控制器拥有自己的caching并且已启用时，您的磁盘的专用DRAMcaching将被禁用。 这是一个安全措施，因为使未受保护的（从功率损失）caching可以使您的数据处于风险之中。
有时候可以安全地重新启用它（例如：你的磁盘有掉电保护，或者你的控制器正确地向下游磁盘传播ATA FLUSH / FUA命令），但是如果没有testing你不能100％确定。 某些RAID控制器甚至不允许重新启用磁盘的专用DRAMcaching。
出于testing目的，您可以尝试重新启用它并重新testing您的arrays，但要非常小心地投入生产。 如有可能，请使用具有掉电保护function的SSD（Crucial M550 / M600具有部分保护function，而Intel S3500 / 3700 / DC系列则具有全功率保护function）。