Chosen Solution

Hello. I have a late 2013 27” iMac - 14,2 - 3.5GHz - … EMC is 2639 … 3TB internal fusion drive. The overall system performance when using this internal drive as the startup is very bad. However, duplicating a large file (like 100GB) on this internal drive to itself seems pretty fast. But, copying that same file to a decent external drive is incredibly slow (the finder says it will take ~3 days to copy that 100GB file to an external drive). Is that still symptomatic of a failing drive itself, or something else in the file system/file hardware? (I wouldn’t want to install a new SSD drive, only to have the problem be something else.) Thanks. -Allan Update (12/11/2018) From the system report, here’s the INTERNAL Apple drive: Available: 1.47 TB (1,469,475,217,408 bytes) Capacity: 3.12 TB (3,121,506,295,808 bytes) Mount Point: /Volumes/Macintosh HD File System: APFSWritable: YesIgnore Ownership: NoBSD Name: disk2s1Volume UUID: FBDF963E-B821-3C1A-9039-4032684E3CF3 Physical Drive: Device Name: APPLE SSD SD0128F Media Name: AppleAPFSMediaMedium Type: SSDProtocol: PCIInternal: YesPartition Map Type: UnknownS.M.A.R.T. Status: Verified …and here’s the EXTERNAL LaCie: Available: 3.91 TB (3,906,058,018,816 bytes) Capacity: 4 TB (4,000,577,273,856 bytes) Mount Point: / File System: APFSWritable: YesIgnore Ownership: NoBSD Name: disk4s1Volume UUID: 4E6B39CB-90B3-3448-ABBB-1CA5A9FE4959 Physical Drive: Device Name: Rugged USB-C Media Name: AppleAPFSMediaProtocol: USBInternal: NoPartition Map Type: Unknown

OK, if you have a fusion drive internally, that consists of an SSD blade and a standard hard drive. Open disk Utilities to see exactly what drives you do have. Just to verify, are the both drives original Mac equipment? If so, I suspect your internal stand drive may be failing. If not Apple original we are dealing with a whole new ball game. Also, please tell me which drive is designated as the start up drive in about this Mac. UPDATE This is the composition of a Fusion Drive iMac Intel 27" EMC 2639 Blade SSD Replacement iMac Intel 27" EMC 2639 Hard Drive Replacement How to Break a Fusion Drive: https://www.macworld.com/article/2015664…