Question CMR drive with 256MB cache?

[tmckay]

Looking to buy a 4TB WD Blue and looks like the only available ones here are WD40EZAX and WD40EZAZ.
According to WD product brief, WD40EZAX is CMR and WD40EZAZ is SMR, both with the same 256MB cache. Last year I bought a WD40EZRZ which I know is CMR with only 64MB cache.
From my limited knowledge, an indicator of a CMR drive is the smaller cache size. 256MB cache indicates that a drive is likely to be SMR. I found no review whatsoever of the WD40EZAX so it looks like it's a new model, can't found any mention of it anywhere except from this post.

Should I look for WD40EZRZ or buy the WD40EZAX?

 

[kerberos_20]

Should I look for WD40EZRZ or buy the WD40EZAX?

ezrz is old model, no longer produced, ezax is new model
if you buy old model, youll be just helping cleaning up someones inventory

 

[fzabkar]

To me, this question is a can of worms.

Here is the Product Brief:

https://documents.westerndigital.co...duct-brief-western-digital-wd-blue-pc-hdd.pdf

WD40EZAX - 4TB - CMR - 180 MB/s - 256 MB cache​

WD40EZAZ - 4TB - SMR - 180 MB/s - 256 MB cache​

Why would WD build an SMR version if the equivalent CMR version has the same capacity and performance? The only thing that makes sense to me is if the SMR version had less heads by virtue of its capacity, or if the CMR version had less (cheaper) cache.

If we go to WD's warranty checker site, we find that the EZAX (CMR) has 4 heads while EZAZ (SMR) has 6 heads. All other things being equal, the 4-headed drive should be about 20% faster than the 6-headed one. However, the CMR and SMR models in the product brief must have the same number of heads by virtue of their identical performance, so what would be the point of making an SMR model?

WX42AC2HES45 <- serial number​

WD40EZAX-00C8UB0 <- model number and family code​

VENRP2LP <- family name​

5400​

256M​

SATA3 6GB/S​

4.0 TB​

4HD <- 4 heads​

PC STD​

WX12D412TA82 <- serial number​

WD40EZAZ-00SF3B0 <- model number and family code​

VENICER <- family name​

5400​

256M​

SATA3 6GB/S​

4.0 TB​

6HD <- 6 heads​

STD​

That said, WD's product sheet doesn't make any mention of the drive's family. The family code is in the model number's suffix, ie C8U versus SF3. It is likely that WD updates the internals of the drive and gives it a newer family code without updating the product brief.

This blog is maintained by a data recovery researcher:

What WD and HGST hard drives are SMR?
https://hddscan.com/blog/2020/hdd-wd-smr.html

 

[tmckay]

ezrz is old model, no longer produced, ezax is new model
if you buy old model, youll be just helping cleaning up someones inventory

To me, this question is a can of worms.

Here is the Product Brief:

https://documents.westerndigital.co...duct-brief-western-digital-wd-blue-pc-hdd.pdf

WD40EZAX - 4TB - CMR - 180 MB/s - 256 MB cache​

WD40EZAZ - 4TB - SMR - 180 MB/s - 256 MB cache​

Why would WD build an SMR version if the equivalent CMR version has the same capacity and performance? The only thing that makes sense to me is if the SMR version had less heads by virtue of its capacity, or if the CMR version had less (cheaper) cache.

If we go to WD's warranty checker site, we find that the EZAX (CMR) has 4 heads while EZAZ (SMR) has 6 heads. All other things being equal, the 4-headed drive should be about 20% faster than the 6-headed one. However, the CMR and SMR models in the product brief must have the same number of heads by virtue of their identical performance, so what would be the point of making an SMR model?

WX42AC2HES45 <- serial number​

WD40EZAX-00C8UB0 <- model number and family code​

VENRP2LP <- family name​

5400​

256M​

SATA3 6GB/S​

4.0 TB​

4HD <- 4 heads​

PC STD​

WX12D412TA82 <- serial number​

WD40EZAZ-00SF3B0 <- model number and family code​

VENICER <- family name​

5400​

256M​

SATA3 6GB/S​

4.0 TB​

6HD <- 6 heads​

STD​

That said, WD's product sheet doesn't make any mention of the drive's family. The family code is in the model number's suffix, ie C8U versus SF3. It is likely that WD updates the internals of the drive and gives it a newer family code without updating the product brief.

This blog is maintained by a data recovery researcher:

What WD and HGST hard drives are SMR?
https://hddscan.com/blog/2020/hdd-wd-smr.html

Thanks for the answers, so the EZAX should be good to buy?

 

[fzabkar]

I don't know whether you are going to get a 4-head or 6-head model. WD's product brief doesn't really help in this regard. It could even be that the warranty checker is wrong.

I feel reasonably confident that the EZAZ is SMR, but I can't find any corroborating evidence that would confirm that the EZAX is CMR.

When you do get a new HDD, you can determine the number of heads with HD Tune:

http://www.hddoracle.com/viewtopic.php?f=59&t=650

 

[Misgar]

I prefer CMR over SMR, especially when copying large 50GB MP4 video files from NVMe temporary storage to hard disk. With such large files, the hard disk cache size is totally irrelevant. It fills up in a couple of seconds.

If you part fill an SMR drive, then delete thousands of files (hundreds of GB), subsequent write operations will take longer, as disk management shifts data around due to overlapping tracks. I find SMR drives frustratingly slow when compared to CMR drives, after they've been used for several months.

When archiving data, e.g. backups that will rarely be accessed, potentially longer SMR write times might be acceptable, but if the hard disk is used on a daily basis, stick to CMR. SMR allows the drive manufacturer to cram more data on each platter and reduce the drive manufacturing cost per Terabyte accordingly. This saving may (or may not) be passed on to the customer.

https://forums.servethehome.com/index.php?threads/wd-red-avoiding-the-smr-pitfall.27535/