From: matthew patton <pattonme@yahoo.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] cache on SSD makes system unresponsive
Date: Fri, 20 Oct 2017 00:12:16 +0000 (UTC) [thread overview]
Message-ID: <541215543.377417.1508458336923@mail.yahoo.com> (raw)
In-Reply-To: 541215543.377417.1508458336923.ref@mail.yahoo.com
> It is just a backup server,
Then caching is pointless. Furthermore any half-wit caching solution can detect streaming read/write and will deliberately bypass the cache. Furthermore DD has never been a useful benchmark for anything. And if you're not using 'odirect' it's even more pointless.
> Server has 2x SSD drives by 256Gb each
and for purposes of 'cache' should be individual VD and not waste capacity on RAID1. Your controller's battery-backed RAM is for write-back purposes if you want to play that game. Cache is disposable. You can yank the power cord out of the drive and the software will continue. Now if you were TIERing, that's a different topic and depends on the implementation whether or not you can lose a device. The good ones make sure the SSD can disappear and nothing bad happens.
> 10x 3Tb drives. In addition there are two
> MD1200 disk arrays attached with 12x 4Tb disks each. All
Raid5 for this size footprint is NUTs. Raid6 is the bare minimum.
next parent reply other threads:[~2017-10-20 0:12 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <541215543.377417.1508458336923.ref@mail.yahoo.com>
2017-10-20 0:12 ` matthew patton [this message]
2017-10-20 6:46 ` [linux-lvm] cache on SSD makes system unresponsive Xen
2017-10-20 9:59 ` Oleg Cherkasov
[not found] <640472762.2746512.1508882485777.ref@mail.yahoo.com>
2017-10-24 22:01 ` matthew patton
2017-10-24 23:10 ` Chris Friesen
[not found] <1928541660.2031191.1508802005006.ref@mail.yahoo.com>
2017-10-23 23:40 ` matthew patton
2017-10-24 15:36 ` Xen
[not found] <1714773615.1945146.1508792555922.ref@mail.yahoo.com>
2017-10-23 21:02 ` matthew patton
2017-10-23 21:54 ` Xen
2017-10-24 2:51 ` John Stoffel
[not found] <1540708205.1077645.1508602122091.ref@mail.yahoo.com>
2017-10-21 16:08 ` matthew patton
[not found] <1244564108.1073508.1508601932111.ref@mail.yahoo.com>
2017-10-21 16:05 ` matthew patton
2017-10-24 18:09 ` Oleg Cherkasov
2017-10-19 17:54 Oleg Cherkasov
2017-10-19 18:13 ` Xen
2017-10-20 10:21 ` Oleg Cherkasov
2017-10-20 10:38 ` Xen
2017-10-20 11:41 ` Oleg Cherkasov
2017-10-19 18:49 ` Mike Snitzer
2017-10-20 11:07 ` Joe Thornber
2017-10-19 19:09 ` John Stoffel
2017-10-19 19:46 ` Xen
2017-10-19 21:14 ` John Stoffel
2017-10-20 6:42 ` Xen
2017-10-19 21:59 ` Oleg Cherkasov
2017-10-20 19:35 ` John Stoffel
2017-10-21 3:05 ` Mike Snitzer
2017-10-21 14:33 ` Oleg Cherkasov
2017-10-23 10:58 ` Zdenek Kabelac
2017-10-21 2:55 ` Mike Snitzer
2017-10-21 14:10 ` Oleg Cherkasov
2017-10-23 20:45 ` John Stoffel
2017-10-20 16:20 ` lejeczek
2017-10-20 16:48 ` Xen
2017-10-20 17:02 ` Bernd Eckenfels
2017-10-24 14:51 ` lejeczek
-- strict thread matches above, loose matches on Subject: below --
2017-10-19 10:05 Oleg Cherkasov
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