Mass storage Flashcards
What is the name of the bit-sized needle on the end of an actuator? (HDD)
A transducer
True or false: There are not just one, but two read/write heads. One on the top of the platter and one on the bottom?
True
What is platter RPM and what is its alternate name?
Revolutions per minute, Spindle Speed
What sizes do HDD come in? (Inches)
2.5, 3.5
What are three cons of using a HDD?
Spin-up time at start, moving parts are a liability, generates heat quickly
True or false: SSDs use flash memory chips
True
M.2 uses keys to tell you what the port is capable of. What are the keys to indicate mass storage use?
B, M, B+M
What is the more efficient alternative to Multi-level cell (MLC)
Single-level cell
What is sequential read/write?
Reading/Writing to long files or things that are in order on the memory storage device.
When do Sequential read/write speeds come into play in real life situations?
Video editing, large files.
What unit of measurement is used when measuring Random read/write speeds?
Input Output per second. IOPS. “4k Read” also implies the data chunk used in the test is 4KB large. So the test consisted of the drive randomly finding and writing 4KB chunks as fast as it could.
What is latency usually measured in?
Nanoseconds, microseconds
What real life situation would benefit from high random read/write speeds?
A file server
What are the speeds of Sata 1, 2 and 3?
1.5, 3 and 6 gbps. 20% overhead for the encoding scheme means the speeds drop to about 150, 300, 600 MBps.
What is an external enclosure?
A casing of external HDDs or SSDs. Ex: A raid box.
What is the maximum length of a sata cable (internal)?
1 meter
What is AHCI?
Advanced Host Controller Interface - made to optimize spinning drives
What does NVMe mean?
Non-volatile memory express
What does SCSI stand for and what is it used in?
Small computers system interface. Used on servers.
True or false: There is a an alternate SCSI called Serial attached SCSI that uses serial delivery instead of parallel?
True. It also supports sata drives.
Explain Raid 0, 1 (and duplexing), 5, 6, 10 and 01
0 - Striped 1 - Mirrored 5 - Stripe w/ parity 6 - Stripe w/ parity with 2 parity blocks per HDD instead of one 10 - A1, A1 | A2, A2 01 - A1, A2 | A1, A2
What is the min drive amount for raid 6?
4 - Each drive has two parity pieces instead of one (as is the case with Raid 5)
because of the additional parity space needed, and the fact that raid 6 allows for 2 disk failures, this means 4 drives are required.
Min drive amount for raid 5?
3
Raid software vs hardware - Which is more efficient?
Hardware. Software can strain your OS if too many disks are added. Hardware has its own chips and setup through flash rom.
True or false: Some hardware raid controllers allow for you to hot-swap bad drives?
True
