από nikosal » 21 Δεκ 2008, 01:24
Χμ, ενδιαφέρον θέμα. Τα πλεονεκτήματα του δίσκου είναι δεδομένα (με γεια!), τα μειονεκτήματα, σύμφωνα με τη wikipedia είναι:
-> DRAM based SSDs have a higher vulnerability to abrupt power loss.
-> Limited write (erase) cycles: Flash-memory cells will often wear out after 1,000 to 10,000 write cycles for MLC, and up to 100,000 write cycles for SLC[9], while high endurance cells may have an endurance of 1–5 million write cycles (many log files, file allocation tables, and other commonly used parts of the file system exceed this over the lifetime of a computer).[24] Special file systems or firmware designs can mitigate this problem by spreading writes over the entire device (so-called wear levelling), rather than rewriting files in place.[25] In 2008 wear levelling was just beginning to be incorporated into consumer level devices.[9] However, effective write cycles can be much less, because when a write request is made to a particular memory block, all data in the block is overwritten even when only part of the memory is altered. The write amplification, as referred by Intel, can be reduced using write memory buffer.[26] In combination with wear leveling, over-provisioning SSD flash drives with spared memory capacity also delays the loss of user-accessible memory capacity. NAND memory can be negatively impacted by read and program (write) disturbs arising from over accessing a particular NAND location. This overuse of NAND locations causes bits within the NAND block to erroneously change values. Wear leveling, by redirecting SSD writes to lesser-used NAND locations, thus reduces the potential for program or write disturbs.[27] An example for the lifetime of SSD is explained in detail in this wiki.[dubious – discuss] SSDs based on DRAM, however, do not suffer from this problem.
-> Slower write speeds: As erase blocks on flash-based SSDs generally are quite large (e.g. 0.5 - 1 megabyte)[9], they are far slower than conventional disks during small writes and can suffer from write fragmentation,[28] and in some cases for sequential writes.[15] SSDs based on DRAM do not suffer from this problem. It should also be noted the smaller the blocks being written the more pronounced the problem becomes.
-> Lower storage density: Hard disks can store more data per unit volume than DRAM or flash SSDs, except for very low capacity/small devices.
-> RAM based SSD require more power than hard disks, when operating; and they still use power when the computer is turned off, while hard disks do not.[29]
Αφήνω κατά μέρος το ότι είναι ακριβοί, σίγουρα θα μειωθεί η τιμή τους γρήγορα.
Το έψαξα γιατί μου έκανε εντύπωση ότι έχουν περιορισμένο κύκλο ζωής. Να μου πείτε, οι κοινοί σκληροί τι είναι, αθάνατοι;
Desktop στο σπίτι: ubuntu 14.04 σε AMD Athlon II 435X3 (αναβάθμιση) με Samsung SSD 500GB
Desktop στην εργασία windows xp (δυστυχώς!)
Laptop: ubuntu 13.10 σε i3 (new install) με Samsung SSD 250GB
Netbook των τέκνων: lubuntu 13.10 σε Atom 450 (new install)
Smartphone: Android 4.1.2 Jelly Bean σε Samsung Nexus S
Tablet: Android 4.4.2 KitKat σε LG G pad 8.3
