Q1: Is there a utility/tool or operation guide for SMART command?
A1: A SMART attribute description for StorFly drives is available. Customers can issue standard SMART commands to get SMART data.
Q2: What is Virtium’s over-provisioning percentage?
A2: SSD manufacturers implement various methods to improve performance, and one of these is to allocate more free space, a process known as over-provisioning. Virtium’s over-provisioning percentage for standard part numbers is typically 7% of the capacity. For custom part numbers, this value can be set to any value that customers need.
Q3: What is the spare capacity of an overprovisioned drive (resulting in reduced user capacity) used for?
A3: The over-provisioned capacity that nets 240GB, for example, is primarily used for flash management to help reduce write amplification and improve wear-leveling efficiency as well as increase the number of spare blocks for bad/worn block replacement resulting in improved drive endurance.
Q4: Can a SATA 6Gb drive be configured for 3Gb access only (i.e. can automatic selection of either 6Gb/3Gb be disabled)?
A4: Fixed 3Gb mode can be supported in a custom configuration (under custom part#).
Q5: How does StorFly SATA negotiate the SATA link speed?
A5: During the power-up sequence, the host will issue Identify Drive, Mode Sense, and Read commands. The StorFly device will respond with Identify Device data (specifically word 76 – Serial ATA capabilities) as shown in the StorFly datasheet. The drive will negotiate from its highest SATA link mode (SATA-III/6Gb) first and then work down to lower modes until a successful negotiation is established.
Q6: Do StorFly drives support TRIM?
A6: All StorFly drives support TRIM.
Q7: How do StorFly drives maintain steady performance over the life of the drive? Does Virtium precondition its drives?
A7: All Virtium drives are preconditioned (program/erase drive 2 times) during test so documented performance numbers are based on “steady-state” performance meaning that no appreciable performance degradation should occur over life of drive. If a customer wishes to see the same steady-state performance in their application then they should also precondition the drives before deploying. Otherwise, the TRIM feature in the drive firmware helps to minimize performance degradation, although there may be some small latency effects at certain times when the drive is conducting flash management activities including TRIM, garbage collection, mapping table updates, etc. This is true of all SSDs from any vendor.
Q8: Does Virtium fully test each drive before shipping it out?
A8: Yes, Virtium’s production test covers a full drive write on every drive. This means we write and verify every LBA of each drive before we ship out. We also test at industrial temperatures for I-temp rated configurations.
Q9: When do Virtium drives become read only?
A9: Drives become read only when spare = 0, regardless of life remaining.
Q10: Do Virtium drives stop working when the SMART attribute life remaining is zero?
A10: The drive will still run when life remaining = 0 and will continue to run for a while. However, it is not recommend to keep running when life = 0 as it can fail any time after that.
Q11: Could you clarify the difference between SMART attribute 0xA1 and 0xF9?
A11: SMART attribute 0xA1 (161) = Number of remaining spare blocks SMART attribute 0xF9 (249) = Percentage of remaining spare blocks If the initial spare block count is 100, then both values will be identical – 50 spare blocks remaining equals 50%. If the initial spare block count is 110, then the values will be different – 50 spare blocks remaining equals 45%. Additionally, users can benefit from Virtium’s vtView software, which provides a time-based estimate of the remaining spare blocks versus a percentage.
Q12: What is the NAND endurance of MLC, iMLC, and SLC and how do I read it?
A12: CE class (MLC, *1X with 3-year warranty) Example: 240 GB, 601 TBW / 2.3 DWPD (3 years) XE class (iMLC, offers 7X endurance compared to CE with 5-year warranty) Example: 240 GB, 4207 TBW / 9.6 DWPD (5 years) PE class (SLC, offers 30X endurance compared to CE with 5-year warranty) Example: 256 GB, 23,880 TBW / 51 DWPD (5 years) *Endurance baseline = one entire drive-write-per-day for the entire warranty period. Results are higher/lower based on various read/write workloads.
Q13: What is the difference between M.2 keys: B, M, and B+M?
Currently an M.2 SSD has either one of three key types: B, M, or B+M. 1) ‘B’ keying (pins 12-19) gives PCI Express SSDs up to 2x lanes of bandwidth. 2) ‘M’ keying (pins 59-66) provides PCI Express SSDs with up to 4x lanes of bandwidth. Note: Even with 2x lanes of bandwidth, a ‘B’ keyed M.2 SSD still gives 10Gbit/s performance, whereas the 4x lanes on ‘M’ give up to 20Gbit/s. 3) M.2 SSDs with B+M keying maximize compatibility in both slots, and will operate with 2x lanes of bandwidth. See image below.
Q14: What is Virtium’s secure erase and how does it work?
A14: The user issues a SATA command to implement a secure erase, which will physically erase all user data blocks including spare areas. Virtium’s secure erase is persistent over power cycles. If the drive loses power during the erase, it will automatically resume erasing upon subsequent power cycles.
Q15: What is AHCI?
A15: AHCI is a technical standard that specifies the operation of Serial ATA (SATA) host bus adapters in a non-implementation-specific manner. AHCI stands for Advanced Host Controller Interface. AHCI mode must be enabled to use Native Command Queuing (NCQ) or Hot Plugging (aka Hot Swapping) functionality as well as Power Management in SATA storage devices.
Q16: Why does Virtium use tantalum capacitors in our designs?
A16: We use tantalum capacitors as a part of our vtGuard power down protection technology for StorFly and TuffDrive SSDs. Tantalum capacitors have the best energy density for small form factor SSDs like eUSB, CF, M.2, mSATA, Slim SATA, and CFast. Tantalum capacitors also offer a wide operating temperature range making them ideal for use in industrial environments.
Q17: What type of conformal coat does Virtium use?
Q18: What is MIL-STD-810? Which Virtium products are compliant?
A18: MIL-STD-810 is a US military standard that specifies a set of environmental conditions (i.e. extreme temperatures, high shock/vibration) that the product must meet for compliance. All Virtium StorFly SSDs support the MIL-STD-810F environmental standard. Tests conducted include EMI, temperature, operating/non-operating shock, operating/non-operating vibration, and altitude testing.
Q19: What is garbage collection?
A19: Flash memory is grouped into pages, which is the smallest amount of flash that can be written. Pages are collected into blocks, which is the smallest amount of flash that can be erased. Flash memory must be erased before it can be programmed. Due to these two different sizes, during operation, pages are rewritten to other pages and the older pages are left behind in the block. Garbage collection is the process where the controller reclaims blocks by moving all valid pages from a block so that it can be erased and used again to store new data. This combining of the still valid blocks into a new block will increase writes to the flash beyond what the user is requesting, also known as write amplification. This is analogous to HDD defragmentation where all the files are realigned to improve performance. In SSDs, this realigning of data is creating space for new data to be stored in the flash.
Q20: What is write amplification (WA) or write amplification factor (WAF)?
A20: Write amplification (WA) is defined as the number of writes to the flash divided by the number of writes by the user. A perfect system would have a WAF of 1. Sequential writes have a WAF near 1 due to the ease of aligning the write data to the page and block boundaries. As entire blocks get rewritten, entire blocks can be erased and the garbage collection is minimized. Random writes will generate a much higher WAF due to all the garbage collection required to move valid data to create spare blocks to be written to. See FAQ on garbage collection.
Q21: What happens when the SSD's spares run out during a large file transfer?
A21: When an OS writes a big file, it typically breaks down the big file into several write commands. If the spare SMART attribute reaches 0 during this large 50MB file write operation, the first few write commands (0 to 10MB, before spare is 0) should still go through. The last few write commands (10 to 50MB, after spare is 0) will abort, resulting in an incomplete file.
Q22: Will vtView work with first generation VSFA series SSD?
A22: vtView is not supported on first generation VSFA series.
Q23: How to tell if a drive is in SATA II 3Gbps?
A23: Check ATA-ACS word ID:76 bit 3 which should show “0”. This bit is automatically disabled when the drive is reinitialized with max SATA interface speed of 3Gbps.