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Alignement automatique avec Windows Server 2008...

Alignement automatique avec Windows Server 2008...

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Une bonne nouvelle qui a pu passer inaperçue !

Avec Windows Server 2008, par défaut, l'alignement des partitions sur les disques sera automatique (ou presque : si la taille de stripe est supérieur à 1M  diskpart pourra encore être nécessaire).

cf. page 30 du document suivant : Performance Tuning Guidelines for Windows Server 2008

NTFS aligns its metadata and data clusters to partition boundary by increments of the cluster size (which was selected during file system creation or defaulted to 4 KB). In earlier releases of Windows, the partition boundary offset for a specific disk partition could be misaligned, when it was compared to array disk stripe unit boundaries. This caused requests to be unintentionally split across multiple disks. To force alignment, you must use diskpar.exe or diskpart.exe at the time that the partition is created.

In Windows Server 2008, partitions are automatically offset by 1 MB, which provides good alignment for the power-of-two stripe unit sizes that are typically found in hardware. If the stripe unit size is set to a size that is greater than 1 MB, the alignment issue is much less of a problem because small requests rarely cross large stripe unit boundaries. Note that Windows Server 2008 defaults to a smaller power-of-two offset for small drives.

If alignment is still a problem even with the default offset, you can use diskpart.exe to force alternative alignments at the time of partition creation.

En fait l'alignement est défini en fonction de la taille du disque par la clé de registre HKLM\SYSTEM\CurrentControlSet\Services\VDS\Alignment

image

Lire : 1Mo au delà de 4 Go

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