I have an old array that I first built about 9 years ago mainly for serving media and running docker containers. It consists of 5 x 2.5" HGST 7K1000 drives (one parity, 4 data). The drives are CMR and have done a great job. Unfortunately, they are showing their age and you cant buy replacement 7K1000s anymore as gone out of service some time ago. So I've been exploring my options.

 

I was hoping to just replace each drive over time with a new equivalent but it seems that 1TB 2.5" CMR drives are not generally available. I could swap to 3.5" drives but that would mean replacing my entire array in one go and is a bit expensive for me.

 

So I guess there are two options: 1) go for a 1TB 2.5" SMR drive and accept its suboptimal, or 2) use a 1TB 2.5" SSD and accept that performance may wane over time (this is based on the SSD only array posts I've read).

 

My inclination is option 2 but wondering if any more experienced hands have a better solution that I haven't come across.

 

Attached download of SMART log for current suspect disk (Reallocated event count has jumped up significantly).

 

server-smart-20240521-1513.zip

9 minutes ago, PeteBa said:

I was hoping to just replace each drive over time with a new equivalent but it seems that 1TB 2.5" CMR drives are not generally available. I could swap to 3.5" drives but that would mean replacing my entire array in one go and is a bit expensive for me.

This IS your path forward.  Get yourself the largest drive you intend to use as you upgrade the individual drives.  The physical size (2.5" or 3.5") is only limited by your case. 

Take a picture of your disk info under Main for reference.

Shut down array.

Use that large drive to replace the parity drive. 

Boot system up.

Go into Tools > New Config.  Check Preserve Pool slots and Uncheck Preserve Array slots. 

Now assign all the disks in the previous spots according to the pic you tooke except parity.  Assign the new large drive in the parity spot instead of the original.

This should leave you with big parity drive + 4 original 1TB data drives.

Finish array creation and it will initiate a parity check.  Your data will be preserved.

 

Later on...

 

Swapping out data drives will require some data shuffling.  My suggestion would be to add a new large drive, migrate all your data to that new drive, then use New Config to remove all the old empty drives by simply not assigning them during the process above.  That will leave you with 1 parity and 1 data drive.  You can if course expand that at your convenience.

 

Good luck.

 

 

A good quality SSD should still perform OK without trim, and better than the disks, but note that you will not be able to directly replace a 1TB disk with a 1TB SSD, because Unraid creates a smaller partition on flash media, so it will complain they are smaller.

@Veah, I'm pretty happy with the array size and unfortunately the priority is on replacing the failing data drive rather than parity. I like the idea of 2 x 4TB 3.5" CMR drives but case constraints make it difficult to migrate there incrementally.

 

@JorgeB, thanks for the info on partition size. I think that blows the SSD option out of the water as I want to be able to easily swap out a failing drive. I take it there is no way to "shrink" my existing HDD partitions to allow future direct replacement with an SSD ? (suspect wishful thinking)

 

Feels like the 2.5" HDD market is slowly dying with no natural replacement for the 7K1000 drive. Suspect I will opt for a cheap SMR drive and maybe buy a few lottery tickets at the same time  

3 minutes ago, PeteBa said:

I take it there is no way to "shrink" my existing HDD partitions to allow future direct replacement with an SSD ? (suspect wishful thinking)

Not that I know of.

Why not switch to using 2TB 2.5" HDD - they are reasonably priced nowadays.

They will be SMR, though in my experience most Seagate SMR disks perform reasonably well with Unraid, WD and Toshiba on the other hand can be considerably slower, dog slow sometimes.

@itimpi, yep, JorgeB took my words. I just cant find any 2.5" CMR drives anymore which is a shame but understandable given the competition from SSDs. Unfortunately, I dont see a good incremental route forward for unRaid setups like mine.

 

@JorgeB, interesting point about Seagete SMR disks. I'll take a look at the specs but dont think they'll tell me much about unraid performance. Any references you could point me at ? My experience with SMR is at the horrible end of the spectrum.

5 minutes ago, PeteBa said:

I'll take a look at the specs but dont think they'll tell me much about unraid performance.

There won't be, basically it's my own experience, I have several SMR drives, and Seagate SMR drives, 2.5" and 3.5", usually perform reasonably well, sometimes not much difference vs CMR, other brands can be terrible, have an array with Toshiba SMR drives that every few minutes writes at like 5MB/s for 1 to 2 minutes.

I really like 2.5" drives because they are low power and you can fit a lot of them in a server, example since I'm currently replicating an fs to a 4 SMR drive zfs pool:

 

 

This pool also performs well for SMR:

 

 

This one not so much, used for WORM data:

 

That is very useful. I might look into the ST1000LM049 with 128MB cache and 7200rpm. Looks to be closest fit to what I have and currently on sale near me. Again, thanks for all the insight.