Date: Mon, 24 Mar 2014 13:10:20 -0400 From: Allan Jude <freebsd@allanjude.com> To: freebsd-current@freebsd.org Subject: Re: geli TRIM support Message-ID: <533066FC.5040805@allanjude.com> In-Reply-To: <20140321155348.2945e05e@gumby.homeunix.com> References: <alpine.BSF.2.00.1403201257080.59665@roadkill.tharned.org> <d763caea-4e0b-4c36-a802-6032f896ecd1@email.android.com> <20140321155348.2945e05e@gumby.homeunix.com>
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This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --C3Km0LGUo26retegsCPe1wkVbDBAsAsFm Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2014-03-21 11:53, RW wrote: > On Thu, 20 Mar 2014 19:34:04 +0000 > Mike C. wrote: >=20 >> I was actually googling about this yesterday and found no more info >> then the thread you posted. >> >> So its seems that nothing was done related to this so far? >> >> Which means using trim+geli is problematic. >=20 > These days SSD devices have static wear-levelling so you don't need to > maximize the number of free blocks, just maintain a small pool. You can= > do that by not partitioning the whole device and leaving a few percent > unused. I'm not sure what you would do if the device had already been > written to though, if FreeBSD has a command to trim a device I don't > know what it is. You could just use Linux's hdparm from a live CD. >=20 > You should also be OK if you have a non-geli UFS partition with > sufficient free space on the same device.=20 >=20 >> I was using my ssd with UFS+trim+geli in my laptop. But even before >> noticing the lack of support changed my setup... since the laptop has >> both a ssd and hdd I am now using zfs+geli in the hdd. I have 2 >> partitions in the ssd and I'm using it for log/cache. >=20 > I've been considering that, but I did have a couple of concerns: >=20 > 1. l2arc sounds like it would be much less effective outside of > servers because, AFAIK, the cache doesn't survive a reboot. >=20 > 2. the l2arc cache turns reads on the filesystem into writes to the > SSD. >=20 > =20 > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.o= rg" >=20 1. There is work to make a persistent L2ARC, but it is not finished yet 2. Having an L2ARC (or ZIL for that matter) on the same SSD that the files are on, is only going to hurt. Using an L2ARC takes up more RAM, leaving less for the primary ARC, and as was pointed out about, turns reads into writes. Reading from the L2ARC partition is not going to be any faster than reading from the main data partition, so I don't see the point. Same goes for writes to a ZIL. If your laptop has only 1 drive, an SSD, then you probably just want to use the entire thing for the ZFS pool, rather than partitioning it to use the advanced features that are meant to use SSDs when the pool is NOT SSDs. --=20 Allan Jude --C3Km0LGUo26retegsCPe1wkVbDBAsAsFm Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (MingW32) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJTMGb+AAoJEJrBFpNRJZKfTO0P/RSaRCiEMM4K2JEYAO5RYgAM Lpgy2r2v//+BXAVe0PY2jAXqpdMARyyoKezeQZCwayl1BM1xedyDuZPJF4Lwac7Q qb0wTe6jN0MPgaNH/XaifDgdpS6AJ8AhEH3GGQALW+yPJWLkWbt09sfgow7E2a8i 6cYS4gu2NA4H9NSC8G9MBK0cSwh1Woq1zf/jC/MhH9UDJHRcqqkD97DfqIDibULt gu8nwmpPOx0Jjge6PumpwVCgIvfSUsmS4+9OUgFquoOAZt8jRUFMvoneIiMR21Mx D6n06jZh2WifgNlBlIRijw+bRJI6Cr+srU8w3imwJ3GodmGju6pVAgvBFDEFjCny 7srf75XW060ucyhiS9pWQRDpg1RRtelovYNhtBA1VWn07QX+JmnkIrPenfOEUSO8 88hMGOnSHv/0acH4ZIf9MRwUEILFK2vvwZTW5qKdoPPckkYo5ZFHK/jkePaKXsbO z1OVmAjtQazu2IR1xaTzifJvAX9cOLlQ+q6P9jocc1F3NW2rGnYzZqdDuIDR2tPU +FA9QCxV1klKpJrMDkFdCTSI9pyV83fhiVGL2abFJyHjZQGwoFiqALDygZLklT8o rYhldP4oTun5Vm2ZNXf2s2KaOZX2cGdsNpf+8enZCw3S6M+l0ykDO/P50kWQ+3Kp Q8X2mf/1icy+MBqaFCVU =FrtD -----END PGP SIGNATURE----- --C3Km0LGUo26retegsCPe1wkVbDBAsAsFm--
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