A few weeks ago it was announced that the manufacturers of mechanical hard drives or HDD they used the SMR technology in your units. Has existed enough confusion about what this technology implies and the units that comprise it. We have been in contact with Toshiba, one of the leading HDD manufacturers on the market, to obtain all the information about it.
The controversy is given because the packaging did not specify that the units made use of this technology. A technology that in some areas may pose some performance issue. For him average user that an HDD makes use of SMR technology is not a problem. Let's see if we can solve all the doubts.
What is SMR (shingled magnetic recording)
Technology shingled magnetic recording (staggered magnetic recording) o SMR is a data recording technique on HDD drives. Is used for increase the storage density and overall capacity of hard drives.
Conventionally, HDD write data on non-overlapping magnetic tracks placed in parallel to each other (perpendicular recording). The system SMR allows staggered writing on tracks that are superimposed on the previously written track.
There is therefore a partial overlap between tracks, making them more 'narrow' and increasing the density. It is basically a structure similar to typical roofs made with tiles. This approach is given by the physical limitations of the magnetic recording heads. This physical limit prevents the magnetic recording heads from being the same width as the reading heads, making the recording heads wider.
Such overlapping track architecture makes the writing process more difficult by partially overwrite an adjacent track. If the adjacent track has valid data, it must be rewritten.
Thus the SMR units are divided into many track adding zones that require overlapping and have to be rewritten completelyor. It is a ligament technology similar to flash blocks in solid state drives.
Self-managed SMR devices simplify management complexity when using firmware. Host managed SMR devices depend on the operating system to understand how the drive is handled. They only write sequentially to certain regions of the drive.
Data management on HDD drives with SMR
Managed Device HDDs appear to the host as if they were non-fragmented drives. This means that the host does not require any special protocol. The hard disk drive is the one that manages the handling of the data in regards to tiered storage.
Your translation layer operation on firmware controlled tiles have similarities to SSD drives. This is because LBA addresses are not very correlated with the disk structure.
Aggregate-only zones are very slow for random writing, so the write is first sent to a PMR cache (CMR). The hard drive moves data to SMR zones when it is not being used.
Using these drives in RAID configurations can cause cache overhead, generating minute breaks. A faulty firmware can also generate an error when asked to read a never written address. Both cases are interpreted as a drive failure by the RAID controller.
Due to this area structure, SMR drives also suffer from write amplification when there is a lot of 'garbage'. Despite this, the issue with SMR HDDs is with write speeds, not longevity. This is why some SMR hard drives support TRIM.
There are SMR units that are managed by a host, requiring strict adherence to a special protocol dictated by the host. Because it is the host who manages the tiered storage, it is necessary to write sequentially so as not to destroy data. The HDD unit will refuse to execute commands that violate this protocol.
System that combines management by the host and administration by the HDD itself. The unit can manage the storage of the 'shingled' and will execute any command that the host provides. It will not be taken into account if the command is sequential or not.
However, the host knows the drive has fragmentation and has the ability to query the HDD fill levels. Allows the host to optimize writes to provide a tiered solution. This makes the unit flexible and backward compatible at the same time.
SMR implementation on HDDs
Increasing the capacity of magnetic hard drives or HDD is not easy, because there are some technical limits. The first of these technical limits is in the HDD dimensions, which is limited because they are standards-based. So not possible to physically make HDD drives larger, so other methods are sought.
What SMR allows is increase the capacity of the disks or platters inside the hard drives. Increasing the density of data that can be stored on a storage unit has its counterpoints. The SMR technology is affecting the writing speed, specifically the random writing speed.
Toshiba is aware of this particularity and its impact on NAS (Network Attached Storage) systems. This is why Toshiba confirms that N300 drives, intended for these storage systems, They do NOT use SMR technology. So users who have Toshiba N300 series hard drives have nothing to fear.
Toshiba wanted to highlight that they work with manufacturers of laptops and desktop computers to choose the most suitable units. But outside of the range of NAS and the like, there is no heavy use of write speed.
We want to highlight that this technology is not negative, on the contrary, it allows to increase the capacities of the HDD. In commercial uses, such as a secondary desktop HDD there is no problem, because it is usually used occasionally. For NAS systems it could generate work speeds lower than expected, but in the Toshiba N300 SMR is not implemented.
Toshiba drives with SMR
Toshiba also informs us of the units that make use of SRM technology. The HDD manufacturer tells us that P300 units for desktop computers, in two models make use of this technology. These storage units are intended for All-in-One computers and desktop computers. They are specifically:
- P300 6TB - HDWD260UZSVA (Bulk version - no box or accessories)
- P300 4TB - HDWD240UZSVA (Bulk version)
Similarly, the L200 units for laptops, consoles and external storage drives, in some cases, they also take SMR technology. Toshiba tells us that the HDDs with SRM within the L200 range are:
- L200 2TB - HDWL120UZSVA (Bulk), HDWL120EZSTA (Retail), HDWL120XZSTA (Retail)
- L200 1TB - HDWL110UZSVA (Bulk), HDWL110EZSTA (Retail), HDWL110XZSTA (Retail)