From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Any pros or cons of using full disk versus partitons? Date: Thu, 14 Apr 2011 18:11:59 +1000 Message-ID: <20110414181159.48a2086e@notabene.brown> References: <07a801cbfa12$64b8a950$2e29fbf0$@gmail.com> <20110413.132112.102552472.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: CoolCold Cc: David Brown , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Thu, 14 Apr 2011 11:57:47 +0400 CoolCold wro= te: > On Thu, Apr 14, 2011 at 12:55 AM, David Brown wrote: > > On 13/04/11 22:21, David Miller wrote: > >> > >> From: "Matthew Tice" > >> Date: Wed, 13 Apr 2011 13:38:39 -0600 > >> > >>> So of course it technically doesn't matter but are there certain > >>> (non-apparent) repercussions for choosing one over the other? =A0= It seems > >>> to > >>> save a couple steps by using the whole disk (not having to partit= ion) - > >>> but > >>> is that it? =A0One thing I'm thinking about the pros of using par= titions is > >>> if > >>> all your disks (or some) are different sizes - then you can set t= he > >>> partition sizes the same. > >> > >> First, you sent this to "linux-raid-owner" instead of just > >> "linux-raid". =A0The former goes to me, not to the mailing list. > >> > >> I've corrected it in the CC: > >> > >> Second, to answer your question, for some disk label variants you > >> risk over-writing the disk label if you use the whole device > >> as part of your RAID volume. =A0This definitely will happen, for > >> example, with Sun disk labels. > > > > Using whole disks in the raid will make it easier for replacing dis= ks - you > > don't have to worry about partitioning them. =A0You can just plug t= hem in and > > use them. =A0If you have some sort of monitoring scripts and hot pl= ug disks, > > you may be able to avoid any interaction at all on disk replacement= =2E > > > > On the other hand, using partitions gives you lots more flexibility= =2E You can > > do things such as use a small partition on each disk to form a raid= 10 array > > for swap, while using a bigger partition for data. =A0Or perhaps yo= u want a > > very small partition on each disk as a wide raid1 mirror, for your = /boot > > (not that you need so much safety for /boot, but that it's easier t= o boot > > from a raid1 with metadata format 0.90 than from other raid types). > Just my 2 cents: I've faced problems when newer disk was smaller than > old disk two or three times, so using partitions now with setting som= e > free space at the end - something near 80 or 100 megabytes. You don't need partitions to do this. Just use the --size option to md= adm. NeilBrown >=20 > If your system is located on the same disks which holds useful data, > it might be useful to split data into another mountpoint/block device > and let system skip fs check on startup and produce booted server, > which is helpful in case of system crash/powerloss and dirty > fs/breaked raid. RAID assembly problems may be caused by crappy > controller like lsi 1068e which was hanging the whole system and > desync data writes on disks on SMART request or completely on it's > own. >=20 >=20 > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-rai= d" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at =A0http://vger.kernel.org/majordomo-info.htm= l > > >=20 >=20 >=20 -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html