Is it possible to mix hard disks in DS215j ?

[L&LD]

What size of drive would I need for the OS please ? (Synology DSM, with only a few packages).

A pair of 500GB hdd's in RAID1 is still much more than is needed for the NAS os. But they would do.

What I recommend and install though is identical drives as what I'm using for the data drives. The spare capacity is not wasted either. It is used as a backup location for the most critical files of the data array (on a weekly or monthly or both, cycle).

While even 128GB sized drives (or even smaller) would work (and maybe even make using ssds worthwhile) for the NAS os, that is not the best overall use of the NAS bays.

With identical drives installed on all the bays and the drives arranged into at least two RAID1 arrays (depending how many drive bays are available), the NAS is much more versatile and I feel more dependable too (similar vibration characteristics are programmed into all drives).

 

[PolarBear]

Thank you L&LD. Food for thought ....

 

[System Error Message]

identical drives are better and some controllers may not like different drives. However i have used 2 different drives of same capacities in raid0 before on realtek chip and they worked fine. The speed however will be 2x the slowest drive.

 

[HellDiver]

Synology NAS units mirror the DSM OS across ALL disks in the NAS, no matter what way you set up the RAID or not.

 

[sfx2000]

can mix drives, just resist the urge to combine them into a single volume...

Should also note than in mixed arrays (Raid0/1/5), the smallest drive size will determine the overall size of the Array, and speed will generally be limited by the slowest disk (for example, if one has one 5400RPM drive, and three 7200 RPM drives, the 5400 RPM drive will limit the others)

If one does use mixed drives, the best approach here likely would be to dedicate shares to the drives - and be careful of running into the JBOD problem, as LVM might go down that path if not careful...

 

[System Error Message]

JBOD isnt a preferred solution, its good if other solutions like mirroring, striping or such arent available as is the case with external drives. Its a capacity alternative to raid 0 without the performance but also you only lose data on the drive thats lost. The main problem with combining disks is that its easy to lose an array, has happened to me often but never to the point where it couldnt be recovered, only a restart and a few commands.

For me the only time i lose arrays is because of cabling (WD blacks can shake things apart) and instability (too high overclock) but never lost any data or the array itself even with raid 0. So if you are putting drives inside a device, raid 0 is better than JBOD. There are many different arrays including complicated ones that can make use of mixed drives capacities.