Write Caching - Enable or Disable

Vidi link:

http://www.sevenforums.com/tutorials/10392-write-caching-enable-disable.html



How to Enable or Disable Write-Caching for a Storage Device in Windows 7

Information:
Write caching in a connected storage device refers to the use of high-speed volatile memory to collect write commands sent to data storage devices and cache them until the slower storage media (either physical hard disks or low cost flash memory) can accommodate them. Most devices that use write caching require that power be supplied continuously.


This will show you how to enable write caching to have better performace for a storage device, or disable write caching for quick removal of a storage device without having to use Safely Remove Hardware.
Tip Tip
If high data transfer performance is your main concern, you should enable both of these settings in OPTION TWO below:

In the Removal Policy section, select the Better Performance option.
In the Write-caching policy section, select Enable write caching on the device (if the system hardware and storage device support these features).

Warning:
You must be logged into a administrator account to be able to do this tutorial.

OPTION ONE
Disable Write Caching for Quick Removal

Note:
This option is usually the best choice for storage devices that you are likely to remove from the system frequently, such as USB flash drives, SD, MMC, Compact Flash, or similar memory cards, and other similar externally attached storage devices.

When you select the Quick Removal option, Windows 7 manages commands sent to the device using a method called write-through caching. In write-through caching, the device operates on write commands as if there were no cache. The cache may still provide a small performance benefit, but the emphasis is on treating the data as safely as possible by getting the commands to the storage device. The main benefit is that you can remove the storage device from the system quickly without risking data loss. For example, if a flash drive were to be accidentally pulled out of its port, the data being written to it is much less likely to be lost.

1. Open the Control Panel (icons view), and click on the Device Manager icon.

2. In Device Manger, double click on Disk drives to expand it, then double click on the listed storage device that you want to disable write caching for. (slika 1)

3. Click on the Polices tab. Under the upper Removal policy section, select (dot) Quick removal, or check the Turn off Windows write-cache buffer flushing on the device box, and click on OK. (slike 2-4)


4. Click on Yes to restart the computer to apply. (slika 5)
WARNING: This will restart the computer immediately. You should save and close anything else that you are working on first.

OPTION TWO

Enable Write Caching for Better Performance

Note:
This option is usually the best choice for storage devices that must provide the highest possible performance and that you intend to not remove from the system frequently, such as internal hard disk drives. If you choose this option and the device is disconnected from the system before all of the data is written to it (such as if you remove a USB flash drive), you could lose data. When using this option for a storage device (ex: USB flash drive), you must use Safely Remove Hardware to disconnect the device safely to prevent possible data loss.

When you select the Better Performance option, Windows 7 uses a method known as write-back caching. In this method, the storage device itself is allowed to determine whether using the high-speed cache will save time completing the write commands. If it will, the device signals to the computer that the data has been stored successfully even though the data may not actually be present in the storage device yet (such as the hard disk or flash memory). This method markedly increases the throughput of storage operations, which are often a major bottleneck for system performance overall. However, if the power supplied to the device (ex: external hard drive) fails for any reason, any data still in the cache (that the computer system believes is safely stored) could be lost.

By default, Windows 7 uses cache flushing. This means that the system will periodically instruct the storage device to write all data waiting in the cache to the storage device. When you select Turn off Windows write-cache buffer flushing on the device, you turn can turn off these periodic commands to transfer the data. Not all devices support all of these features.

1. Open the Control Panel (icons view), and click on the Device Manager icon.

2. In Device Manger, double click on Disk drives to expand it, then double click on the listed storage device that you want to enable write caching for. (slikaA)

3. Click on the Polices tab. Under the upper Removal policy section, select (dot) Better performance. (slika B, slika C)
NOTE: By default, Enable write caching on the device is also checked. If not, then check it as well.

4. To Turn Off Windows Write-cache Buffer Flushing on the Device
WARNING: To Prevent data loss. Do not check this option unless the storage device has a separate power supply that allows the device to flush it's buffer in case of a power failure.

A) Select (check) the Turn off Windows write-cache buffer flushing on the device box.

5. Click on OK.

6. Click on Yes to restart the computer to apply. (slika D)
WARNING: This will restart the computer immediately. You should save and close anything else that you are working on first.

That's it,

U svakom slucaju pogledajte link na samom pocetku
ili
http://www.sevenforums.com/tutorials/10392-write-caching-enable-disable.html
jer je tu lepse prikazano...

Po svezoj instalaciji Win7 ovo je iskljuceno right ?
Posto mi komp radi 24h, kad nestane struje a ovo je ukljuceno moze da dodje do gubitka podataka kazu oni, al svakako i kada je iskljuceno isto se moze desiti

A zasto ovo treba raditi ?

Ako je iskljucen Write Caching, upis na ssd ce biti nizak (rezultat merenja slab) pa ga treba ukljuciti da bi porasla (znatno) brzina upisa...

Za SSD je ovo manje bitna opcija, jer neki SSD-ovi i ignoristu tu opciju. Intel X25-x su recimo je ignorisali (nisu imali pravi cache ) pa su rezultati bili isti u oba slucaja.
Nisam isprobao kako je na drugim SSD-ovima, bas me zanima.

Ma alfa neb i zemlja...
Koliko se ljudi samo dosad zalilo da im "ne valja ssd" i kad im je recno da ukljuce write caching sve im je "proradilo" kako treba, ma "poleti" ssd nakon toga...

Sad sam probao na m4 bez write caching, sve je OK OSIM 4K write - 3MB/s
Siguran sam da je na X25-x bilo drugacije.

Istina, razlicito se ponasaju SSD-ovi po ovom pitanju, zavisno od kontrolera koji imaju u sebi.

Na C300, kao i na tom m4 (sto znaci, mogli bi da generalizujemo - na Marvell kontroleru ), kada je write caching iskljucen, primecuje se ogroman pad za 4K upis... jednocifrene brojke, obicno ~4MB/s, videli smo to na forumu u par navrata u prethodnih par meseci... a ponekad cak ispod, kako si nam ti svojim primerom pokazao
Na HyperX-u 3K, on the other hand, jako sam tesko uspeo da uocim razliku izmedju ukljucenog i iskljucenog write caching-a, a namerno sam ga gasio da bih video kako se ponasa u tim uslovima - AS SSD nije pokazivao ama bas nikakvu razliku (osim standarne 1-2 MB/s varijacije), 4K upis je bio isti... CDM slican slucaj, 4K polje za upis pokazuje iste/slicne vrednosti... tek sam ga video u 4K QD32 polju, i to reda velicine 20-ak MB/s.
Zaista zanemarljivo, posto su tu vrednosti i onako visoke... a opet, ni blizu pada kakav je primetan na C300/m4.

E sad, da li je tako i na svakom SF-2281 SSD-u, to vec ne znam...

Kada sam uzeo Vertex 4 u startu sam istestirao sve opcije ali nisam video neku bitnu izmedju write-caching on/off.
Evo sad na brzinu:

ON


OFF

A da li je to na Intel-u i onda imaš li RST instaliran, da li je u AHCI; bez RST i nema uvek velike razlike...

blackbear je napisao(la):

Kada sam uzeo Vertex 4 u startu sam istestirao sve opcije ali nisam video neku bitnu izmedju write-caching on/off.

Kliknite za proširenje...

Mozda si mogao da probas QD32 kolonu, recimo, tu ja videh promenu za 3K... ovako nema nikakve razlike, istina.

mdm je napisao(la):

A da li je to na Intel-u i onda imaš li RST instaliran, da li je u AHCI; bez RST i nema uvek velike razlike...

Kliknite za proširenje...

Nista Intel, AMD 880g cipset + AHCI mod.

CAR
Mozda si mogao da probas QD32 kolonu, recimo, tu ja videh promenu za 3K... ovako nema nikakve razlike, istina.

Kliknite za proširenje...

Probao, nema. :wave: