tuto:linux:tunning_hdd
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Les deux révisions précédentesRévision précédenteProchaine révision | Révision précédente | ||
tuto:linux:tunning_hdd [2013/06/25 20:45] – root | tuto:linux:tunning_hdd [2016/10/27 21:15] (Version actuelle) – [Tunning HDD] root | ||
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====== Tunning HDD ====== | ====== Tunning HDD ====== | ||
+ | ===== mdadm ===== | ||
+ | [[https:// | ||
===== sysfs ===== | ===== sysfs ===== | ||
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Spécifie si c'est un ssd (0) ou classique (1). | Spécifie si c'est un ssd (0) ou classique (1). | ||
- | ==== tuning cfq ==== | + | ===== tuning cfq ===== |
https:// | https:// | ||
+ | |||
+ | http:// | ||
* **back_seek_max** : Backward seeks are typically bad for performance, | * **back_seek_max** : Backward seeks are typically bad for performance, | ||
- | * **back_seek_penalty** : Because of the inefficiency of backward seeks, a penalty is associated with each one. The penalty is a multiplier; for example, consider a disk head position at 1024KB. Assume there are two requests in the queue, one at 1008KB and another at 1040KB. The two requests are equidistant from the current head position. However, after applying the back seek penalty (default: 2), the request at the later position on disk is now twice as close as the earlier request. Thus, the head will move forward. | + | |
* **fifo_expire_async** : This tunable controls how long an async (buffered write) request can go unserviced. After the expiration time (in milliseconds), | * **fifo_expire_async** : This tunable controls how long an async (buffered write) request can go unserviced. After the expiration time (in milliseconds), | ||
* **fifo_expire_sync** : This is the same as the fifo_expire_async tunable, for for synchronous (read and O_DIRECT write) requests. The default is 125 ms. | * **fifo_expire_sync** : This is the same as the fifo_expire_async tunable, for for synchronous (read and O_DIRECT write) requests. The default is 125 ms. | ||
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* **slice_idle** : This specifies how long CFQ should idle while waiting for further requests. The default value in Red Hat Enterprise Linux 6.1 and earlier is 8 ms. In Red Hat Enterprise Linux 6.2 and later, the default value is 0. The zero value improves the throughput of external RAID storage by removing all idling at the queue and service tree level. However, a zero value can degrade throughput on internal non-RAID storage, because it increases the overall number of seeks. For non-RAID storage, we recommend a slice_idle value that is greater than 0. | * **slice_idle** : This specifies how long CFQ should idle while waiting for further requests. The default value in Red Hat Enterprise Linux 6.1 and earlier is 8 ms. In Red Hat Enterprise Linux 6.2 and later, the default value is 0. The zero value improves the throughput of external RAID storage by removing all idling at the queue and service tree level. However, a zero value can degrade throughput on internal non-RAID storage, because it increases the overall number of seeks. For non-RAID storage, we recommend a slice_idle value that is greater than 0. | ||
* **slice_sync** : This tunable dictates the time slice allotted to a process issuing synchronous (read or direct write) I/O. The default is 100 ms. | * **slice_sync** : This tunable dictates the time slice allotted to a process issuing synchronous (read or direct write) I/O. The default is 100 ms. | ||
+ | ===== tuning deadline ===== | ||
- | ==== tuning deadline ==== | + | http:// |
* **fifo_batch** : This determines the number of reads or writes to issue in a single batch. The default is 16. Setting this to a higher value may result in better throughput, but will also increase latency. | * **fifo_batch** : This determines the number of reads or writes to issue in a single batch. The default is 16. Setting this to a higher value may result in better throughput, but will also increase latency. | ||
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* **write_expire** : This tunable allows you to set the number of milliseconds in which a write request should be serviced. By default, this is set to 5000 ms (five seconds). | * **write_expire** : This tunable allows you to set the number of milliseconds in which a write request should be serviced. By default, this is set to 5000 ms (five seconds). | ||
* **writes_starved** : This tunable controls how many read batches can be processed before processing a single write batch. The higher this is set, the more preference is given to reads. | * **writes_starved** : This tunable controls how many read batches can be processed before processing a single write batch. The higher this is set, the more preference is given to reads. | ||
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===== Script ===== | ===== Script ===== | ||
tuto/linux/tunning_hdd.1372193141.txt.gz · Dernière modification : 2013/06/25 20:45 de root