Hi, I set up RAID using mdadm for the first time 8-9 months ago. As a complete newbie, of which class I still consider myself, I made a bunch of compromises at that time. I am now considering reworking the setup and am looking for some guidance. The system has 5 500GB WD RAID Edition drives. They are all the same model purchased at the same time so they are subject to some of the statistical problems that happen when one does this. The system runs MySQL in Linux and then (typically) runs 3 or 4 VirtualBox VMs running different versions of Windows. 1) The Linux/MySQL stuff is a 3 drive RAID1. (sda/sdb/sdc) 2) The Windows VMs run on a 2 drive RAID0 (sdd/sde) 3) There is a second RAID1 (sda/sdb/sdc) used for backups of the RAID0. The RAID0 is backed up to RAID1 nightly. If the RAID0 fails then I lose 1 day's work. The RAID1 is backed up to another machine every week or two. This is a home network, not a business but I do depend on the data to be there if there's some hardware failure. With a 3 drive RAID1 I figure I'm not in huge danger unless a power supply failure takes out all of the drives. I will copy smartctl -a data at the end of this email ifor all drives n case it might impact any inputs. OK - the problems I have with this arrangement are: 1) I used the older v0.9 metadata. 2) The RAIDs are assembled by the kernel automatically. I do not use an initrd. (Because I don't know how/newer have) 3) I think with 5 disks I could get better performance than I currently get , with similar or better safety using maybe RAID5 or RAID6. Overall, as I see it, I can suffer no disk loss on the RAID0, and can handle a 2 disk loss on the RAID1. (Is that correct?) I'm thinking that with a 5-drive RAID6 I might well get better performance than either of the current RAIDs and (from reading) more protection during a rebuild if one of my drives goes bad. All said, I'm leaning toward RAID6 support everything (MySQL and VMs), probably about 100GB to start with, and then would hopefully scale the size up using the rest of the drives after data is copied over to the new RAID6. I'd build RAID6, copy everything from the current system, ensure the new RAID boots, etc, then eventually blow away the old partitions and resize the RAID 6 larger. Does this make sense? What am I missing or should be thinking about. I have no problem buying maybe 1 new drive now as a spare. The chassis is filled at this time and there's no way to run what I think is considered a hot spare. Thanks in advance, Mark c2stable ~ # smartctl -a /dev/sda smartctl 5.40 2010-10-16 r3189 [x86_64-pc-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net === START OF INFORMATION SECTION === Model Family: Western Digital RE3 Serial ATA family Device Model: WDC WD5002ABYS-02B1B0 Serial Number: WD-WCASYA846988 Firmware Version: 02.03B03 User Capacity: 500,107,862,016 bytes Device is: In smartctl database [for details use: -P show] ATA Version is: 8 ATA Standard is: Exact ATA specification draft version not indicated Local Time is: Wed Dec 29 11:31:35 2010 PST SMART support is: Available - device has SMART capability. SMART support is: Enabled <SNIP> SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0027 238 235 021 Pre-fail Always - 1100 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 308 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0 9 Power_On_Hours 0x0032 099 099 000 Old_age Always - 1363 10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 306 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 15 193 Load_Cycle_Count 0x0032 200 200 000 Old_age Always - 292 194 Temperature_Celsius 0x0022 099 089 000 Old_age Always - 48 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0 SMART Error Log Version: 1 No Errors Logged c2stable ~ # smartctl -a /dev/sdb <SNIP> SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0027 237 236 021 Pre-fail Always - 1108 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 308 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0 9 Power_On_Hours 0x0032 099 099 000 Old_age Always - 1362 10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 306 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 16 193 Load_Cycle_Count 0x0032 200 200 000 Old_age Always - 291 194 Temperature_Celsius 0x0022 098 090 000 Old_age Always - 49 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0 SMART Error Log Version: 1 No Errors Logged c2stable ~ # smartctl -a /dev/sdc <SNIP> SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0027 238 236 021 Pre-fail Always - 1100 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 308 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0 9 Power_On_Hours 0x0032 099 099 000 Old_age Always - 1362 10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 306 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 15 193 Load_Cycle_Count 0x0032 200 200 000 Old_age Always - 292 194 Temperature_Celsius 0x0022 102 091 000 Old_age Always - 45 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0 SMART Error Log Version: 1 No Errors Logged c2stable ~ # smartctl -a /dev/sdd <SNIP> SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0027 238 235 021 Pre-fail Always - 1100 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 296 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 100 253 000 Old_age Always - 0 9 Power_On_Hours 0x0032 099 099 000 Old_age Always - 1299 10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 294 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 29 193 Load_Cycle_Count 0x0032 200 200 000 Old_age Always - 266 194 Temperature_Celsius 0x0022 098 090 000 Old_age Always - 49 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0 SMART Error Log Version: 1 No Errors Logged c2stable ~ # smartctl -a /dev/sde <SNIP> SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0027 237 236 021 Pre-fail Always - 1108 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 297 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 100 253 000 Old_age Always - 0 9 Power_On_Hours 0x0032 099 099 000 Old_age Always - 1300 10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 295 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 17 193 Load_Cycle_Count 0x0032 200 200 000 Old_age Always - 279 194 Temperature_Celsius 0x0022 103 094 000 Old_age Always - 44 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0 SMART Error Log Version: 1 No Errors Logged -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
