On Feb 12, 2010, at 8:20 AM, Felix Buenemann wrote: > Hi Mickaël, > > Am 12.02.10 13:49, schrieb Mickaël Maillot: >> Intel X-25 M are MLC not SLC, there are very good for L2ARC. > > Yes, I'm only using those for L2ARC, I'm planing on getting to Mtron Pro 7500 > 16GB SLC SSDs for ZIL. > >> and next, you need more RAM: >> ZFS can't handle 4x 80 Gb of L2ARC with only 4Gb of RAM because ZFS >> use memory to allocate and manage L2ARC. > > Is there a guideline in which relation L2ARC size should be to RAM?
Approximately 200 bytes per record. I use the following example: Suppose we use a Seagate LP 2 TByte disk for the L2ARC + Disk has 3,907,029,168 512 byte sectors, guaranteed + Workload uses 8 kByte fixed record size RAM needed for arc_buf_hdr entries + Need = ~(3,907,029,168 - 9,232) * 200 / 16 = ~48 GBytes Don't underestimate the RAM needed for large L2ARCs -- richard > > I could upgrade the server to 8GB, but that's the maximum the i975X chipset > can handle. > > Best Regards, > Felix Buenemann > > > _______________________________________________ > zfs-discuss mailing list > email@example.com > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list firstname.lastname@example.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss