SanDisk Extreme Portable SSD 2TB Allocation Unit Size

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SanDisk Extreme Portable SSD 2TB Allocation Unit Size

I've bought this highly-regarded SanDisk Extreme Portable SSD 2TB to use as general backup and storage for my MacBook Pro. I have a good mix of smaller documents and larger media files with an increasing need to accommodate larger (12-20gb) video projects. I have received much conflicting information regarding the default file unit allocation size on this SSD. SanDisk chat support now tells me it is 4096 bytes and cannot be altered by Mac OS, only in Windows. Other forums say it is 1mb by default and can be changed in Mac OS, however with no directions given. I was advised to use ExFat since I must often share collaborative projects with Windows users. I'm no expert and my MacBook's disc utility does not display any allocation unit info. Can anyone advise: 1) if this SSD allocation unit size can be determined and changed in current Mac OS? 2) if so, how or what utility to use? and 3) what unit size might be optimal/suggested for the described purposes?

Many thanks in advance from this relative newbie to a great support community.

Posted on Aug 30, 2019 2:40 PM

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Answer 1

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HWTech

Level 9

60,740 points

Aug 30, 2019 4:45 PM in response to drn3761

What is important is the file system is created on a 4k boundary. 1MB is a multiple of 4k and is a common size. The reason for this is because the internal NAND memory is written and erased in 4k blocks. All recent versions of operating systems understand SSDs and will format them properly so you don't have to worry about it. If you were to use an OS before SSDs became common, then you would need to worry about making sure the SSD is formatted on 4k boundaries.

If you are formatting the drive with exFAT, then make sure to format it using macOS Disk Utility since Windows may use different allocation sizes which macOS won't recognize.

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Answer 2

etresoft

Level 9

51,126 points

Aug 30, 2019 5:24 PM in response to drn3761

Can you clarify something? Are you going to share this entire drive with other people using Windows? Meaning, you are going to give them the drive?

You said you were going to use this as “general backup and storage”. Those two uses are not compatible. Do NOT give people your backup drive. If you want to share a drive with Windows users, a small USB flash drive would be better. If you need to share massive files, I’m guessing a smaller SSD would still be better. You can get some really big USB flash drives.

If you don’t need to have this disk directly connected to a Windows machine, then you don’t need to use ExFAT.

If you want to use the machine with Time Machine, I strongly advise partitioning the disk into at least two partitions so that one partition can be dedicated to Time Machine. You will thank me later. Ideally, make the Time Machine partition 2-3 time the size of all of the disks you will be backing up. The smaller your Time Machine volume, the more problems you will have with it.

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Answer 3

drn3761 Author

Level 1

8 points

Sep 3, 2019 7:26 AM in response to HWTech

Thanks for your help. I suppose my consideration was primarily driven for the desire not to waste a lot of disk space unnecessarily with perhaps a less efficient allocation unit size. My average total system file size is currently 362K, but will likely substantially increase with the new video project demands. That was a driving factor for the 2TB SSD purchase. I'm relieved by your reminder that the common 1MB block size is well-founded and certainly not unreasonable - and probably a lot better than I first thought.

I'll also be certain to use the mac's Disk Utility for the exFAT format since I require sharing some of the SanDisk SSD's duties with another internal Windows workstation.

Again, many thanks for your presence here, the prompt response and great advice.

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Answer 4

drn3761 Author

Level 1

8 points

Sep 3, 2019 9:45 AM in response to etresoft

Thanks etresoft for your help. To clarify: We're a small outfit with two MacBook Pro workstations and one Widows platform and a rather rapidly increasing amount of video creation/editing work. We've been getting by with Cloud backup and sharing multiple flash drives -- certainly ok but not optimal. My original thought was to have the SanDisk 2TB SSD do double duty as backup and storage for all three. Maybe a bit naive and overly optimistic about that (appreciate your diplomacy). Your advice is well-taken and we've now seen the light about the advantages of splitting those functions with another SSD.

The SSD's are for our internal use only -- we use flash drives or Google Drive typically when necessary to share project files externally. Our collective field experience in the video arena drew us to the advantages and flexibility of the durable and portable nature of the SanDisk SSD -- even though they currently live in the office.

Thanks also for your insight and suggestions with the Time Machine partitioning and volume issues. We're not experts -- that voice of experience is much appreciated.

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SanDisk Extreme Portable SSD 2TB Allocation Unit Size

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