You cannot mix SAS and SATA within a virtual disk, so if the virtual disk is using SATA drives then the replacement needs to be SATA.
Dear Support, I have a Linux server with a hardware raid behind a PERC 6/i controller (as per the lsscsi command) [2:0:0:0] cd/dvd TEAC DVD-ROM DV-28SW R.2A /dev/sr0[4:0:32:0] enclosu DP BACKPLANE 1.10 -[4:2:0:0] disk DELL PERC 6/i 1.22 /dev/sda[4:2:1:0] disk DELL PERC 6/i 1.22 /dev/sdb[4:2:2:0] disk DELL PERC 6/i 1.22 /dev/sdc Also, I'm getting this very often: megaraid_sas 0000:02:00.0: 202961 (608338067s/0x0002/FATAL) - P-a-t-r-ol Read found an uncorrectable medium error on PD 05(e0x20/s5) at e900c8b7 That is coming from from the megaraid_sas linux kernel module. In the output it mentions PD 5, which is physical disk 5. The problem happens with /dev/sdc, which is the linux block device representing the mirror of two 2 TiB drives on Virtual Disk 2 through the perc 6/i. From time to time that mount point get slower and slower falling below 5M/s when writing. And, when I execute: megacli -LdPdInfo -a0| sed -n '/^Virtual Drive: 2/,$p'   ---------------------------------------------------------------------------------------------------------------- Virtual Drive: 2 (Target Id: 2)Name :texasd1RAID Level : Primary-1, Secondary-0, RAID Level Qualifier-0Size : 1.999 TBMirror Data : 1.999 TBState : OptimalStrip Size : 64 KBNumber Of Drives : 2Span Depth : 1Default Cache Policy: WriteBack, ReadAheadNone, Direct, No Write Cache if Bad BBUCurrent Cache Policy: WriteThrough, ReadAheadNone, Direct, No Write Cache if Bad BBUDefault Access Policy: Read/WriteCurrent Access Policy: Read/WriteDisk Cache Policy : Disk's DefaultEncryption Type : NoneIs VD Cached: NoNumber of Spans: 1Span: 0 - Number of PDs: 2 PD: 0 InformationEnclosure Device ID: 32Slot Number: 5Drive's postion: DiskGroup: 1, Span: 0, Arm: 0Enclosure position: N/ADevice Id: 5WWN:Sequence Number: 2Media Error Count: 189Other Error Count: 31Predictive Failure Count: 0Last Predictive Failure Event Seq Number: 0PD Type: SATA Raw Size: 1.999 TB [0xfffffffe Sectors]Non Coerced Size: 1.999 TB [0xffeffffe Sectors]Coerced Size: 1.999 TB [0xffec0000 Sectors]Firmware state: Online, Spun UpDevice Firmware Level: CE02Shield Counter: 0Successful diagnostics completion on : N/ASAS Address(0): 0x1221000005000000Connected Port Number: 5(path0)Inquiry Data: Z1F35954ST3000NC000 CE02FDE Capable: Not CapableFDE Enable: DisableSecured: UnsecuredLocked: UnlockedNeeds EKM Attention: NoForeign State: NoneDevice Speed: UnknownLink Speed: UnknownMedia Type: Hard Disk DeviceDrive Temperature : N/API Eligibility: NoDrive is formatted for PI information: NoPI: No PIPort-0 :Port status: ActivePort's Linkspeed: UnknownDrive has flagged a S.M.A.R.T alert : No   PD: 1 InformationEnclosure Device ID: 32Slot Number: 6Drive's postion: DiskGroup: 1, Span: 0, Arm: 1Enclosure position: N/ADevice Id: 6WWN:Sequence Number: 2Media Error Count: 0Other Error Count: 25Predictive Failure Count: 0Last Predictive Failure Event Seq Number: 0PD Type: SATA Raw Size: 1.999 TB [0xfffffffe Sectors]Non Coerced Size: 1.999 TB [0xffeffffe Sectors]Coerced Size: 1.999 TB [0xffec0000 Sectors]Firmware state: Online, Spun UpDevice Firmware Level: CE02Shield Counter: 0Successful diagnostics completion on : N/ASAS Address(0): 0x1221000006000000Connected Port Number: 6(path0)Inquiry Data: Z1F3593LST3000NC000 CE02FDE Capable: Not CapableFDE Enable: DisableSecured: UnsecuredLocked: UnlockedNeeds EKM Attention: NoForeign State: NoneDevice Speed: UnknownLink Speed: UnknownMedia Type: Hard Disk DeviceDrive Temperature : N/API Eligibility: NoDrive is formatted for PI information: NoPI: No PIPort-0 :Port status: ActivePort's Linkspeed: UnknownDrive has flagged a S.M.A.R.T alert : No --------------------------------------------------------------------------------------------------------------- I have not checked the BIOS to see if the drive is in Predictive Failure ONLINE or OFFLINE because this is a production server. I already have the replacement drive. I also see in the previous output "nquiry Data: Z1F35954ST3000NC000 CE02" so that is a 3 TiB drive used on a 2 TiB mirror correct? I see that Z1F35954 is the serial number that match when I run smartctl (which also shows 3 TiB instead of 2). And also the other drive in this 2TiB mirror seems to be of 3 TiB. The new drive I have is a 2 TiB. Is this information correct from megacli? I'm planning to replace one of the disks (the one with serial number: Z1F35954). Also that disk have many errors ("Media Error Count: 189"). I assume that physically it has bad sectors that are being reallocated. I want to shutdown the server, replace the disk (by using the serial number to identify it) and then it should rebuild by itself correct? (Do I have to force it offline first before removal?). Edit: I found out that the PERC 6/i have a 2 TiB limit. The replacement drive I have is 2 TiB.  Will I run into issues? Because the drives on the mirror are both 3 TiB. What worries me is that for a 2 TiB one that will go down to 1.8x or something.      
Dell R510 PERC 6/i - Read found an uncorrectable medium error